*t7.5>' \|>ril 23, 1910. U. S. DEPARTMENT OF AGRICULTURE. BUREAU OF ENTOMOLOGY— CIRCULAR No. 118. L. O. HOWARD. Entomologist and Chief of Bureau. A PREDACEOUS MITE PROVES NOXIOUS TO MAN. (Pedicvioides ventricosus Newport.) F. M. WEBSTER, TnChargi of Cereal and Foragt Insect Investigations. WASHINGTON : GOVERNMENT PRINTING OFFICE : '»IO BUREAU OF ENTOMOLOGY. L. O. Howard, Entomologist and Chief of Bureau. G. L. Marlatt, Assistant Entomologist and Acting < 'hiefin Absence of Chief . R. S. Clifton, Executive Assistant. Chas. J. Gilliss, ( 'hief < 'lerh. F. H. Chittenden, in charge of truck crop and stored product insect inrestigations. A. D. Hopkins, in charge of forest insect investigations. W. D. Hunter, in charge of southern field crop insect investigations . F. M. Webster, in charge of cereal and forage insect investigations. A. L. Quaintance, in charge of deciduous fruit insect investigations. E. F. Phillips, in charge of bee cultun . D. M. Rogers, in charge of preventing spread of moths, field work. Rolla P. Currie, in charge of editorial work. Mabel Colcord, librarian. Cereai and Forage Insect Investigations. F. M. Webster, in charge. Geo. I. Reeves, W.J. Phillips, C. N. Ainslie, E. 0. G. Kelly, J. A. Hyslop, V. L. Wildermuth, K. A. Vickery, T. 11. Parks, Herbert Osborn, I'iiii 11 1 Luginbill, agents and experts. (II) [Cir. 118] Circular No. 1 18. Issued April . United States Department of Agriculture, BUREAU OF ENTOMOLOGY, L. O. HOWARD, Entomologist and Chief of Bureau. A PREDACEOUS MITE PROVES NOXIOUS TO MAN. (Pediculoidt s Newport Bj F. M. Wi bst] I i biuiji of Cereal and Forage Insect Investigations. INTRODUCTION. While the scientific and medical literature of European countries, ami to some extent of Asiatic countries) contains numerous records of mites attacking man, ii is difficull to determine, from a perusal of this literature, whether <>r ool the mite Pediculoides ventricosus Newport, shown in iu mosl active form \>\ figure 1, has Keen concerned in these attacks. There i- no particular reason why it should not have become noxious i<> man precisely as, and elsewhere than, in America, because ii has doubtless, with it- hosl insect, the Angoumois grain moth, Sitotroga cerealeUa Oliv. (fig. 3), been distributed in grains throughout the warm regions of the globe, wherever these grains have entered into international com- merce. While there is a derided similarity between these attacks on man in Europe and America, the writer is unable to select, from the various instances recorded, a single one in which lie can unhesitatingly -a\ thai tins and nol some other species of mite was responsi- ble for such at tack-. In iii.-in \ casesil is very clearlj to l>e seen thai other and very differ- ent species of mites have been involved in at tacks of a similar nature, both in this country and in Europe. Mere in America such troubles L18] (1) Fig. I. \duli female of Pedicu- loides l 111' ali- domen has become inflated with eggs and young. In tin (ion the mite is nomadic and predatory. Greatly enlarged, drawn from Brack have until recently been commonly attributed to "chiggers," a winch inhabit neither the dried straw nor thrashed grain. The term " cliig- ger" really includes a number of different kinds of mites, notably the young of Trombidium and other insects which inhabit grassy and weedy places and woodlands. This is why it is that people visiting such places are not infrequently attacked and suffer painfully there- from. While our knowledge of the matter remained in this condi- tion, the possibility of confusing the disease discussed herein with others of a much more serious nature was very great, but now that we understand the causes and know that these causes can be re- moved, and the physician enabled to distinguish it from an attack of "chiggers" and prescribe proper treatment, much of this danger and painful annoyance may be eliminated. There is also another point that must not be overlooked, namely, that this mite during its period of greatest activity is almost in- visible to the unaided eye (see fig. 1). Not every practicing physician possesses a micro- scope that will enable him to detect the presence of the mite, even when abundant, but the pustules or wheals caused by it are sufficiently described in the paper by Doc- tors Goldberger and Scham- berg and the one by Doctor Rawles to permit of identifica- tion. Later, when the gravid female mite (fig. 2) is dis- tended with eggs and young, it is more easily detected; hut it is not in this state that if attacks human beings and is thus encountered by tin 1 practicing physician. THE MITE BENEFICIAL IN AMERICA. So far as (he author lias been able t<> determine, the first pub- lished record of the occurrence of this mite in America was by him- self, and was included in a paper printed in the Twelfth Reporl of the Slate Entomologist of Illinois (pp. 1 oO-lol ).'' While assistant to Dr. S. A. Forbes, stale entomologist, he was directed to investi- gate serious injuries to stored grain by the Angoumois grain moth, " For aeon ideration of "chiggers," see Circular No. 77, Bur. Ent., pp. 1-6. b Publi bed in Trans. Dept. Agr. Illinois, vol. 20, 1882. [Cir. 118] Fig. 2. ( a avid female of Pediculoidcs vi ntricosus. Greatly enlarged. (Redrawn from Brucker.) Sitotroga <■< realeUa (fig. 3 i, in southern [llinois, where Messrs. I [alliday Brothers, of Cairo, growers and shippers of wheat, were al thai time experiencing considerable trouble from the ravages of ihis grain moth, inn « . 1 1 1 \ in their grain elevators bul also in barges loaded with wheal to be shipped by river to New Orleans and thence exported by steamer. It was during these investigations thai this mite was discovered attacking the larvae of the grain moth. As the original publication containing the author's observations is becoming more and more difficult i" obtain, thai portion relating to the occurrence of this mite is given here\n ii h in full : Pedicukndes [Heteropus) i is, Newport. About iho 12th of October, 1882, a sack of wheal infested with larva; of the grain moth was received from southern [llinois, which, for wanl of time, was put aside for future inspection, (in the L3th Fio.3. Angoumois grain raoth {Sitotroga cerealcUa): a. Egg and egg-mass; ';, larva in grain of wheat; c, larva; (/, pupa; f, /, moth. Enlarged. (i. (■--/. After Chittenden; b, original.) of November, while examining the grains containing larva?, 1 noticed, in a lot of fifty, three in which the worms were dead, ami on them were numbers of globular, yellow objects, which proved to be a species of mite, Pediculoides < Tleteropus) ventri- Knowing nothing of the predaceous habits of these mites, and the limited literature al hand throwing little light upon the matter, 1 did not pay much attention to the fact of their occurrence until the 12th of December, when upon examining LOO grains with respect to the effect of heal on the larva, I found M of the latter infested by these mites. In the meantime I had learned that this mite was known to be of predaceous habit, in both England and France, having been first discovered by Newport, in I849,in the nests of Anthophora retusa, collected at Gravesend, England, and afterwards described by him under its present name. Ii had also been found in France, in l s,iS . bj Jules Lichtenstein, of Montpellier, and described by him under the name of This gentleman found it in his breeding cages, which it so completi Ij overran that, as he informs me, he could not for six months breed a single specimen ol Symenoptera, of Bupn r Ceramby of some Lepidoptera. [Clr If it has been found by any other persons than these, or in any other parts of the world, previous to its discovery here by me, I have not been able to find the fact recorded. On December 31 and January 1, I examined 100 infested grains of this wheat, which had been continually kept in the laboratory since it was received, and found '.V2 per cent of the worms dead, infested by the mites. While making these examinations I frequently threw the grains containing infested larvae into a shallow glass dish, where they remained on my table until the warm weather during the latter part of February, when the temperature of the laboratory at night was much higher than it had been during the previous cold weather. The effect of the change was soon plainly to be seen. The contents of the dish began to swarm with newly developed mites, and a larva dropped into their midst was imme- diately attacked, and after that its life was of short duration. Larvas placed at some distance from the dish suffered a like infection. To test the matter I placed near the dish some weeds, in the pith of which some larvae were hibernating, and in two days the mites had found and destroyed them. These young mites when first m it iced are very minute, of elongate form, and extremely active, running about in search of larva 1 ; and when one is found they immediately puncture the skin and suck the juices. In a day or two the posterior segments of the abdomen begin to enlarge, and this process continues until the inflated, bladder-like abdomen becomes ten or even twenty times the size of the cephalothorax. During this time they have gradually lost their ambulatory powers, and remain stationary upon their -victims. In the meantime changes equally wonderful have been going on within the abdomen. Eggs are continually forming, and within these the young mites are as continually developing, passing through their entire metamorphosis, which includes thi acquisition of the fourth "pair of legs (an exceptional character among mites), within the abdomen of the mother, from which they make their way as fast as they reach maturity. The females are quite prolific. I have counted frequently from 40 to 50 young and eggs within the abdomen, and believe thai they produce even more. The mothers survive the birth of a large number, if not a majority, of the young. The male I have never found, and 1 am inclined to believe with Mr. Newport, that the species is parthenogenous. The minute size (if these young miles admits of Iheir free access in the larva? of the moth, through the very small opening where this made its entry, and a single mite with its progeny would be sufficient to destroy it. That this is very often the manner of attack is proved by the fact that grains in which the larva is badly infested frequently have no other break in the hull by which evenayoung mite could gain admission. Like the larvae on which they subsist, their development is retarded or increased by the temperature, they being quite active at a temperature of 00° F.; but in colder weather able to remain within the abdomen of the parent for months in a dormant state, awaiting a rising temperature. While, as stated, this was probably the first published record of the occurrence of this Pediculoides in America, the writer has since had reason to believe that it was present many years prior to this date; and, indeed, in t he lighl of information that was obtained during the past year, 1909, it seems altogether probable that it not only occurred but proved noxious to man, in Massachusetts, as early as 1830. The particular reference, however, to which attention is called may be found in the Prairie Farmer for the year 1845, page 216. "I have since observed the male, though only occasionally, [Clr. 118] Much is here made of larvae attacking the stems of wheal above the upper joint, and in connection therewith follows this significant sen- tence: "In one instance nine eggs were round in a single straw, one of which had jusl hatched." Also, in another journal, we are (old tli.it specimens of infested straw were forwarded to the Country Gentleman from Scipioville, N. Y., in 1879, which the sendee stated contained eggs, besides larvae and pupa'. In both cases the larvae were almosl beyond a doubt those of the greater wheat-stem maggot I 1/. romyza arrn i icana Fitch I. According to my 0"w n observal ion, the mites attack the larvae of \feromyza americana in stems of wheat, and one can not fail to be struck by the clearness with which the state- ments jusl given describe larvae of this species in the stems of grain or grass being attacked by these mites, the gravid female of which has oven appearance to the unaided eve of being a minute egg. It therefore seems not improbable thai this mite was abroad over the country at the earlier date, 1845, which would antedate by several years the description of the species in England by Newport, who called attention to the occurrence of this mite as a parasite in the nests of a wild bee (Anthophora retusa L.) in a paper read March 5, 1850, before the Linnaean Society of London." In the account given by Dr. T. \V. Harris in the second edition of his "Insects Injurious to Vegetation," in connection with his discussion of the early occurrences of the barley join tworm (Isosoma hordei Harr. . there are two very significant statements that have until latel\ puzzled the writer greatly. On page 138, edition of 1852, he says: In the summer of (831, myriads of these flies [meaning the adull / oma]were found alive in straw beds in Gloucester, the straw having been taken from the fields the year before. An opinion al thai time prevailed that the troublesome humors wherewith man were then afflicted wer :casioned by the bites of these llif-: ami it is stated thai the straw beds of Lexington, being found to be infested with the same insects, were generally burnt. The second referenc -curs on page l hi of the same volume, in which it isstated thai " about eight years ago [which would be aboul 1844] some of these insects [again referring to the barley jointworm] that had come from a straw bed in Cambridge were shown to me. 'They had proven very troublesome to children sleeping on the bed, their bites or stings being followed l>v considerable inflammation and irri- tation, which lasted several days. So numerous w ere the insects that it was Found necessary to empty the bedtick and burn the straw." Now. to the writer it has always been puzzling that the adults of the barlej jointworm, as thej were described 1>\ Doctor Harris, should have Keen able to bite through bedticking and cause the l'. ription published in Trans. Linn. Soc. Lond., vol. 21, p. 95, L853. I fir lis] eruption described and yet not be able to gnaw through this cloth and make their escape, as every one who has reared these insects in confinement has witnessed their frantic efforts to escape as soon as they gnaw their way out of the straws. The mite Pediculoides ven- tricosus now furnishes as good an explanation of these attacks referred to b}^ Harris as we can expect to secure, after a lapse of three-quarters of a century, with no possibility of obtaining actual proof in the case. In 1884 the writer found this same mite attacking and destroying the wheat strawworm {Jsosoma grande Riley) at Oxford, Inch, and in speaking of the occurrence of this larva and its parasites, he made this statement: Curiously enough, during the time it occupies the stubble in the larval and pupal stage?, it sometimes falls a victim to the mite Pediculoides (Heteropus) ventricosus, which enters the stubble from above after the grain is cut, but whose sense of discrimi- nation is rather poorly developed, and it is finally victorious over the Isosoma larva 1 , its parasites, and the predaceous larvae of Leptolrnchelus dorsalis. The same year, and in the same locality, this mite was again encountered by the writer, attacking the greater wheat-stem maggot in wheat straw, and the remarkable resemblance of the gravid fe- males to minute eggs was again noted. Since that time this Pedic- uloides has been reported by Mr. E. M. Ehrhorn attacking the larvae of the peach twig borer, Anarsia lineatella Zell., in California. The same year Mr. Marlatt reported it as attacking the eggs of the periodical cicada, Tibicen septendecim L. 6 The same year Dr. F. H. Chittenden c stated that this mite attacked the larvae of two species of bean weevil (Bruchus quadrimaculatus Fab. and B. chinensis L.) and destroyed them, often in great numbers. Still later, in 1904, Messrs. W. D. Hunter and W. E. Hinds, in Bulletin No. 45, Division of Entomology, page 107, called attention to its attack on the larvae of the cotton boll weevil. In 1908 Mr. W. Dwight Pierce** stated that this mite is a common weevil parasite in Mexico. In the same publication, page 42, he credited it with being parasitic, not only on the cotton boll weevil, Anthonomus grandis, but also on an allied species, the pepper weevil (A. eugenii Cano). Dr. A. D. Hop- kins informs the writer that in his studies of forest insects he has encountered it attacking the larvae of wood-boring beetles, and at one time, in West Virginia, it caused considerable mortality in his rearing cages, where he was attempting to rear wood-boring longi- corn beetles (Cerambyci(he) and barkbeetles (ScolytidaO, precisely as experienced by M.Jules Lichtenstein in France. " Bui. Hi, Div. Ent,, U. S. Dept. Agr., p. 17, 1898. '■ Bui. I I, n. s., Div. Ent., U. S. Dept. Agr.. p. 101, 1898. . c u. S. Dept. Agr., Yearbook for 1898, p. 217 follows: In the spring and summer of L 909 this peculiar eruptive disease be- came quite |"v\ alent in Philadelphia and neighboring towns. An out- break among 20 sailors upon a private yachl docked in the Delaware River attracted the attention of both thecity and the federal health authorities. The Sur- geon-General of the United States Public Health and Marine- 1 [ospital Service dele- gated Dr. Joseph Goldberger, passed as- sistant surgeon, to pro- ceed to Philadelphia for the purpose of making an in\ estiga- tion of the disease. Aiterexaininingthe 20 sailors, who had been senl to a hos- pital, Doctors Gold- bergerand Schamberg visited the yacht w hence i bey came and made a searching ex- aniinat ion of the con- ditions on board. Their attention was directed to the lad that a number of new- straw mat t resses had been received and t hat t lie disease w as con- fined to those who had slept upon these mattresses or had placed their clothes n | ion t hem. Eleven officers and members of the crew who did not sleep upon t he new mattresses remained entirely free of the disease. At about the same period information was received concerning an eruptive disease prevailing among the sailors of four other boats, plying along the Delaware River. Investigation disclosed the fact thai these boats had also received new straw mattresses, and, further- more, that onl\ those were attacked who slepl upon the mattresses or Otherwise came in contact with them. [Cir. us) Fig. 5.— Lesions cau of the mite Pedicuioidi In this case the eruptions are almost the reverse of those shown in ■ much smaller, mon placed, and confined more to the lower portion of I ere still being very few on either neck or arms. 10 111 addition to these cases among sailors, Doctors Goldberger and Schamberg examined or received authentic information concerning seventy other cases of this disease occurring in twenty different households in Philadelphia and its vicinity. In practically every instance they were enabled to determine that the patient had either recently slept upon a new straw mattress or had freely handled the same. Where only one person in a household was affected, it was found that he was the only one to occupy a bed supplied with a new straw mattress. They were able to trace all of the incriminated mat- t resses to four leading mattress manufactur- ers. Figures 4, 5, 6, and 7, from photo- graphs by Doctor Schamberg, show the condition of some of the victims and illus- trate different forms of the eruption. Careful investiga- tion warranted them inexchuling from con- sideration the ticking of the mattresses and the jute or cotton top- ping contained there- in. The cause of the disease was, therefore, circumscribed to the si ia\v. Repeated in- quiries elicited the in- Fig. 6.— Lesions caused bj b of thi mite Pedit Ho ' usus. formal ion that all of In this figure the eruptions are still more minute, covering the a |. (% m 'in llf-iel lirers entire body, including the arms and neck, the hair having been _ removed from the neck to show their diffusion even on the base of had received, at the the head. The lesions are also less swollen than shown in figure 5. i • „ j 1 . <] jcro- ducing mattresses were made up, wheat straw from a dealer in Salem County, in soul hern New Jersey. One manufacturer had used straw from this source' exclusively in the affected mattresses, while in another case the straw had come from southern Indiana. Finding of a parasite. Doctors Goldberger and Schamberg sifted the straw from a mattress through the meshes of a fine flour sieve upon a large piece of plate glass covered with white paper, (lose scrutiny of the siftings under strong electric illumination soon de- tected some slight motion. The moving particles were touched with [Cir. UN] 11 a needle moistened in glycerine and transferred to a glass slide. Search with the microscope disclosed the presence of a mite of very minute dimensions. The mite was identified for them by Mr. Nathan Banks, expert in A.carina of the Bureau of Entomology, United Slates Department of Agriculture, as very close to, if uol identical with, the P< diculoidi s <■< ntricosus. In order to demonstrate experimentally the etiological relation- ship of the suspected straw mattresses, Doctor Goldberger exposed his bared lefl arm and shoulder for one hour between two mattresses. At the end of about sixteen hours, a num- ber of characteristic lesions appeared upon the arm, shoulder, and chest; Later, three volunteers slept upon the mattresses and each one developed the eruption at the end of about the same period. I )octor ( roldberger later touk some of the sifted si raw, di\ ided it into two portions, and placed il in t wo c 1 ea n Pel ri glass dishes. One of t bese was applied for one hour to t he left axilla of a volunteer. At i be end of From sixteen to seventeen hours the charact erist ic erup- tion was present in the area of the left axilla to which the Petri dish of straw siftings had been applied. The second portion of the st raw siftings in a Petri dish was exposed to the vapor of chloroform under a bell jar with a view to killing any insect or acarine thai might be present. These siftings were then applied to the right axilla of the same volunteer to whose left axilla t lie untreated siftings had Keen applied. The chloroform evidently destroyed in the siftings the agent that was producing the eruption, for do lesions appeared alter the application of the chloroformized -hi ings. [Clr. 118] Fig. 7.- i i ' '1 by bites of the mite I In this case the effect is entirely diffei io\vn in any of ■ ■ i \ . including the arms, but extending over the face and (orehi ilar, inflamed patches. This figure Illustrates the liability of tl mistaken for other mallpox and spotted fi\ er. 12 Doctor Goldberger, further, removed from some straw siftings five minute mites, and, placing them in a clean watch crystal, applied the crystal to the axilla of another volu nt eer. At the end of about sixteen hours following this application five of the characteristic lesions ap- peared on the area to which the mites had been applied. (See fig. 8, from drawing by F. H. Wilder.) INFLUENCES CONTROLLING THE EXCESSIVE ABUNDANCE OF PEDICULOIDES. It will be noticed that Doctors Goldberger and Schamberg made no attempt to discover the underlying causes for the enormous numbers of these mites inhabiting the mattresses involved in their investiga- tions, that problem coming properly within the realm of entomology. When the writer took up this subject with the view of finding out the causes for such an abundance of these mites, Doctors Gold- berger and Schamberg very kindly placed at his disposal every- thing in their posses- sion relating to this epidemic, including the mattress which Doctor Goldberger had himself used in experiments with this mite, carried out by him at the Hygienic Laboratory in Washington. Doctor Schamberg was equally kind in placing at his service all of the material, notes, and photographs in bis possession. Almost at the commencement of the investigation, Dr. William Royal Stokes, of the Maryland state board of health, informed the writer that a similar but less extensive epidemic had shortly before been noted in Baltimore. This he kindly described as follows: The matter was brought to my attention by several persons, who came to the head of the department and complained of the skin eruption described. They stated that, a number of people in a suburban hotel were similarly affected, but I do not remember the number at ibis late date. These persons volunteered the information that they had all been sleeping on some new Btraw mattresses, and that all of the pei ons similarly affected had used these mattresses. [CIr. 118] t w ■*- W* . 8.— Lesions caused by bites of the mite PedictUoides vintricosus. \iiout natural size. 13 I .-aw Doctor Gilchrist, ili>> clinical professor of dermatology al Johns Hopkins University, yesterday, and he gave me the following description of th which he Baw al the health department, f saw two other cases which corresponded w ith these in a general way. "The eruption consisted of about 1,000 wheals, or erythemato-withicarial sp papulo-withicarial lesions. As in the description in the reprint of Doctors < roldberger and Schamberg, of the United States Public Health and Marine-Hospital Service, they varied in size trom a lentil seed to a finger nail, and arc round, oval, orirregular in Bhape. No vesicles or pustules were seen. The eruption was on the neck, chest, abdomen, and hack, and al.- i arms and legs. Itching was present, and all lesions showed evidences of scratching." Besides this, there were several cases reported to the writer from northern Maryland, where farmers in running their wheal through a fanning mill had been simultaneously troubled by a very similar or identical erupl ive disease of the skin. In another instance, a th rasher- man engaged in feeding the unthrashed grain into the cylinder of jg —^ t Ml > "^jS l> \ t\ 1 Wm V / 1 f \ J FlG.9. — Aiiuii oliointv/onn (lsosomalritici). Much enlarged. (From Howard.) the thrashing machine was also affected by a disease of the skin, en- tirely unfamiliar to the attending physician, who could not classify it with any urticaroid dermatitis known to him. After the writer's experience of previous year-, it seemed impossible thai this Pedicu- loides should become sufficiently abundant to cause this dermatitis without there being an excessive abundance of some bos! inseel or insects affecting either the straw or the grain itself. Naturally, the studies made by him in 1882 led him to suspect that the Ajigoumois grain moth (Sitotroga cerealeUa) might he responsible for the abund- ance of the mites. Then, too, the fact that it attacked the wheat- straw worm (foosoma grand* Rilej I in wheat straw led him to suspect that, as this particular species i- not known to occur in the vicinity id' Philadelphia, while it-- near relative, the joint worm (Isosoma ti'iin'i Fitch) (fig. 9), does occur more or less abundantly over the [Clr, l ts| 14 eastern part of the country, this latter species, too, might perhaps be involved. With a view to finding out something of the abundance of the grain moth in New Jersey, from which State was obtained most but not all of the straw entering into the mattresses mentioned by Doctors Goldberger and Schamberg, the writer applied to Dr. John B. Smith, state entomologist, for information. In reply Doctor Smith was kind enough to send the writer an advance copy of the report of his department of the New Jersey Agricultural Experiment Station for the year 1908, and from this publication it was learned that during the summer of that year, owing to favorable weather conditions, this moth developed rapidly in the field and there was great damage to wheat among those farmers who delayed thrashing until September or later. Furthermore, a very large percentage of the wheat crop gathered that year became useless for milling purposes, and so general was the infestation that grain from some localities was entirely barred at mills except when ground for the owner. Some further investigations carried on in eastern Pennsylvania revealed a very similar condition of affairs. It was the straw of 1908, coming mostly from New Jersey, but a small part of it from Indiana, that entered into the mattresses, from the use of which came the epidemic in and about Philadelphia. In order to settle these points, Mr. V. L. Wildermuth, of the Bureau of Entomology, was instructed to examine the straw in the mattress placed at the writer's disposal by Doctor Goldberger. After a day and a half of careful search, only five straws affected by the joint- worm were found. This seemed to entirely eliminate this species from consideration in connection with this particular epidemic. There were, however, many wheat heads remaining attached to the straw, and these heads contained a great many kernels, the contents of which had been, eaten out by the larva 1 of the grain moth. More- over, these eaten kernels contained great numbers of the dead bodies of Pediculoides. That the Angoumois grain moth was the cause of this damage to the wheat was still further proved by the emergence of an adult- moth from these eaten kernels on November 15. The larva? of this moth infested the kernels of wheat before the latter were thrashed. Many of these infested kernels remaining in the straw were included in the materia] going into the manufacture of these mattresses. The greater portion of the living larva' of the moth would develop to adults during May or early June, thus cutting off the food supply of these mites. The mites would therefore very naturally swarm among the straw and, making their way through the cloth covering of these mattresses, attack anything that gave promise of furnishing food and preserving them from starvation. It seems that starvation is the filial outcome, however, for, as already [Cir. 118] 15 stated, no trouble is experienced in using the mattresses after a cer- tain period, which period probablj indicates the termination of the life of the miles infesting the straw. It therefore did nol seem nec- essary to seek further for the primary cause of this eastern epidemic of dermatitis, the center of which seems to have been in and about Philadelphia. A WESTERN EPIDEMU Ol THE DERMATITIS. "While the problem of the epidemic in the East was apparently solved, some of the wheat straw involved therein had come from Indiana, and during the last few years an outbreak of the jointworm (figs. !o ami 11) had been gathering force throughout Ohio, Indiana, and soul hern Illinois, until during the sum- mer of 1 908 \ ei\ seri- ous damages occur- red . [nvesl igation of the insect during previous years had shown that the out- break really began in the more ele"\ ated portions of Virginia, in the upper Shenan- doah Valley, in West Virginia, and in east- ern < )iiio, ;is curly as 190 1, afterwards ad- vancing broadly to the west w ard. During the sum- mer of L908 there came to the Bureau of Entomology from this section of the country a greal nutnber of complaints of serious skin trouble among people engaged in thrashing grain that had been stored for some time in barns, and in some localities it had become difficult to secure help to thrash under such conditions. Also the sai lisorder was encountered by those who used this straw for the purpose of filling bedticks, or as ,-i substitute for felting under carpets, and in one case berry pickers had been attacked when such straw had been used as a mulch for berry |>lani^. This straw came from a. held that had been seriously damaged from jointworm attack in 1908. In one instance a carload of wheat straw was shipped to Pittsburg, Pa., and six men engaged in unloading it were attacked i 18] i 10 Effect of jointwi.i i traw in Held. Note enlargements and distortions. Reduced. (Original.) 16 by some skin eruption, and the horses used in hauling this straw after it was unloaded also suffered from what was seemingly the same disorder. Perhaps the following from a correspondent of the Bureau of Entomology, residing in, southern Ohio, will give a fair idea of the situation on man}' farms in that section of the country: About four years ago a parasite was found when thrashing wheat out of barns. It seemed to affect the victims almost as soon as they got into the mow. The men began to scratch themselves, generally on the neck and on the arms (inside) opposite the elbow, and on the body back and front. The parasites raised welts such as you describe and spread as you in- dicate They have spread to such an extent that farm hands dread them and will not change work with neigh- bors unless they thrash in the field. Hereof Late they are found in wheat straw in the barns, especially if baled. Last week a farmer brought me baled wheat straw that seemed to be alive with them. They attacked every one that went into 1 he barn, and one of my horses that was perspiring from effects of a drive was simply covered with little knots or swollen places and bit and rubbed himself continually. I had to have the straw hauled out and burned and the barn disinfected. The farmer stated thai they were so thick in the shed thai contained the si raw that he had in keep all stuck out of the shed. .Many other similar Letters from towns in Ohio were re- ceived by Doctor Schamberg, particularly from Zanesville, Columbus, Vincent, Springfield, etc., where the affection is popularly believed to he due to "doggers." A physician from the last-named town stated that in the fall of 1908 during harvest and thrashing time he saw in Wash- ington County some 87 eases of the disease iii question. It affected the harvesters and thrashers. This spring he observed 38 cases from contact with straw ticks refilled with straw of last fall's crop. The disease is said to have heen more prevalent last year (1908) than ever before. Information has come from Columbus, Ohio, that potters who used straw for packing crockery ware have heen so badly attacked at times that the entire force of packers has heen off duty. Many rcir. L18] Fi(i. 11.— Female Isosoma in act of depositing ojtk in stem. About life size. (Author's illustration.) 17 times a whole carload of straw bias Kith 30 affected thai the use of it has been abandoned. In Springfield, Ohio, it is said thai the dis- ease was so bad a year or two ago in the lowlands west of the city as seriouslj to tamper the progress of the construction of a large sewer; this, however, blight have been due to attack by other mites. In Zanesville, Ohio, the potters have Keen obliged to abandon the use of Btraw and emplo} "prairie hay" for packing purposes. Doctor Schamberg was also informed by a physician of Pittsburg that a young woman patient had suffered from an affection closelj resembling if nut identical with the one under consideration each time that she had assisted in emptying cases of dishes packed in straw. Both the physician and the patient had come to believe that something in the straw was the cause of the eruption. Indeed, so nearly did the territory from which these complaints came to us coincide with that affected by the jointworm that it created the suspicion, not only among those engaged in the invent iu r a- tions, hut even among farmers themselves, that there must he some connection between the two phenomena. Very many of these cases were brought to tlu> notice of practicing physicians, hut the latter were at a loss to account for the prevalence of this dermatitis, nian\ of them supposing it to be some species of rash that was more or less contagious, the exact nature of which t he\ did not know. The lia- bility of confusion with other vastly more serious contagious diseases, notably smallpox, was of course veiy great. Among these physicians was Dr. Lyman T. Rawles, of Hunter- town, Ind.. who, in May, 1909, undertook a careful study of a number of cases of this dermatitis that had come tinder hi- personal observa- tion, as well as those of some of bis associates. Doctor Rawles's inves- tigations were very carefully made, and the results are exceedingly valuable for the reason that, in the case of this western epidemic, he was able to trace the cause i>\' the skin eruption to the mite (Pedicu- loides ventricosus) and follow this back to the host insect, the wheat jointworm {Isosoma tritici)." It clear- up the obscurity surrounding the cause of this epidemic in the Middle West, a section throughout which the Angoumois grain moth never occurs in excessive abundance excepting in grain that is kept in store, and then only in the more southern portion of Indiana ami Illinois. In May, 1909, Doctor Rawles found in his practice that a very strikingly strange skin disease presented it-elf in his own and the "( )w -iii- to an unfortunate misunderstanding, for which do one connected with these investigations is responsible, I 1 tor B vies did do! receive a proper determination of the mite involved in liis studies of the dermatitis. The entomological nomencla- ture in bis paper, printed in the Journal of the Indiana Stale Medical Association, August, L909, should therefore !"■ corrected by substituting PedicuL for Ditropinotus aurem iridii wherever the latter oameoccure F. M. \Y. [Clr. ns| 18 surrounding country in epidemic form. Through the press notes ii seemed to be quite general over the northern part of the United States, limiting itself to the wheat-growing sections. The people generally affected were farmers and those Irving in small villages or towns where straw is used in beds, under carpets, and around stables to bed stock. Horses and cattle have been seen with a skin disease almost identical with that seen in man. The following incident led him to an investigation as to the probable etiology: A family had cleaned house, refilled the straw ticks of their beds, and placed fresh straw under the carpets, and in about one week the family had developed this peculiar skin disease. In the beds was found a small black fly (Isosoma tritici Fitch) about the size of an ordinary gnat, which at first it appeared to be, but closer observation revealed that it was not of the gnat family. Upon examination of the straw it was found that a large number of the straws were perforated; these perforations were through the wall in the region of the joint, generally about 2 inches from the joint. The perforations were about the size of a small pinhole and ranging in number from ten to thirty in a straw. Upon examining a section of this straw the small black fly was found under many of the openings through the walls. Several flies were examined to ascertain if they possessed a piercing proboscis, and while observing one which had just been taken from under the sheath of the straw, through which then 1 was no perforation over the fly, a small mite was observed crawling over the dead body of the fly. Placing the bodies of several of these flies under the microscope and using a one-fourth-inch objective and a No. 5 eyepiece, it was found that on nearly all flies over which the wall was intact a small mite could be detected, these varying in number from two to four mites to each fly. Upon furthering the observations it was found that the dermatitis lasted after the flies had been observed and exterminated. The following experiments were tried to prove whether it was the fly or the mite that was the etiologic factor in producing the dermatitis. Six live Hies were taken, upon which no mites could be found; these were placed under a watch glass and bound upon the right arm, leaving them in contact with the skin for three hours. Upon the left arm four dead Hies, on which living mites had been observed, were placed under a watch glass and left in contact with the skin for three hours, after which the glasses were removed and resulls awaited. The right arm showed nothing. Upon the left arm there appeared within twelve hours four small wheals, the character and evolution of which are later described. To further the experiments some fresh lesions of patients were scraped and the scrapings examined microscopically, and two of the mites were found in the scrapings. [Cir. 118] 19 [tching is the most prevalent and nrsl symptom to attracl the at tout ion of the patient. It is most persistent and intense during the after part of the aight. At aboul the time the itching was most intense there appeared an urticarial eruption, accompanied, in severe cases, with genera] systemic symptoms, such as rise of temperature from 99 to 102; in one case the temperature rose to 103.8; the pulse rate is accelerated to LOO, or as high as 110— in one case to L30. Other symptoms were intense headache, anorexia, nausea, in sunn' cases vomiting, and a mild form of diarrhea. In severe cases some complained of general joint pains and backache ; in t hese cases t he urine was examined and albumin in small amount was found, but no casts or blood. When the acute symptoms disappeared, so did the albumin. Many patients who suffered from mild cases complained of nothing aside from th< intense itching. If all straw was removed from the beds and house, t lie symptoms would subside in one or two days and completely disappear in a few days more. The lesion, which is typical of the disease, is the urt icaria vesiculosa. The urt icaria 1 Lesion varies in size from thai of a split pea to that of a penn\ : it is surrounded by a pinkish halo, varying in intensity of color from a pale pink to a most brighl pink. The "hive"-like lesion is at first blanched, hut later becomes a rose-red color. It is elevated aboul 1 or 2 millimeters above the skin surface, and is sur- mounted by a small vesicle containing a whitish lluid marking the I dace of i noc u hit ion. The vesicle is aboul I or 2 millimeters in diame ter and (derated about •"> millimeters above the surface of the urti- carial lesion. As the lesion grows old it goes through the process of evolution: (1) It is blanched and has a central vesicle; (2) it is rose- red and the vesicle may become a pustule; (3) it generally recedes to the skin level with scab formation, due to the scratching ; I 1 1 it leaves a brow nidi or greenish-yellow or purple spot on the skin surface. In debilitated patients the markings look not unlike faded indelible- pencil marks. (This was noted in a patient suffering from pulmonary tuberculosis.) These discolorations may lasl for several weeks. The anatomical location of the lesions is generally the hack, -ides, and abdomen, and less frequently the arms and legs. Tin- neck has very few lesions; the lace, hands, and feet have very few or none. The number of lesions depends upon the number of mites, ranging from very few to thousands; in some cases the hack and abdomen have been almost a solid mass of lesions new lesions on the tops of old Lesions, so having Lesions in all stages of development. Later investigations carried out by Mr. Wildermuth, at Lafayette, Ind., during December, L909, and January and February, L910, show that where straw is kept in masses, as in stacks and barns, the mites literally swarm through the straw, and as -nun as an tsosoma or its parasites attempt to gnaw their waj out through the cells in the [Clr. us] 20 straw, the mites enter and kill them before they are able to enlarge the opening sufficiently to enable them to make their escape; indeed, not more than 5 per cent succeeded in escaping. As this represents fairly well the conditions of straw in spring and early summer when it is used for the manufacture of mattresses and on the farms for the filling of straw ticks and as a substitute for felting under carpets, the great number of cases of this dermatitis occurring over the country is not at all surprising, and the indications for the season of 1910 are more favorable for an increase than a decrease in the trouble. OBSCURITY SURROUNDING THE OCCURRENCE OF THIS SKIN DISEASE. The exact nature of this eruptive disease was not at all understood by the medical profession throughout the country. In southwestern Virginia thrashermen suffered from the same disorder, but attributed it to "chiggers" (fig. 12), and local physicians, though skeptical, were themselves unable to correctly diagnose or to account for the trou- ble. As the disease is not serious and passes away in the course of time without leaving the patient in any way permanently injured, it seems to have been passed over by medical men without investiga- tion, excepting by the physicians whose publi- cations have just been cited. Among the peo- ple themselves the erup- Fig.12. Leptusamericanus&tlelt; Leptusirritans at right. Highly tion wis nrob'lblv more magnified. (After Riley.) ' frequently attributed to attacks of "chiggers" or a "rash "than to any other cause, and it is quite likely that this common erroneous interpretation of the origin of the eruption has prevailed generally throughout the country, including the upper Shenandoah Valley in Virginia, where the jointworm was abun- dant as far hack as 1904. It was, consequently, rather unfortunate that, with the beginning of this disorder, an institution in one of the States involved should publish a newspaper bulletin crediting the epi- demics of t his eruption to the attack of "chiggers," and, furl hermore. that a second press bulletin, accentuating the first, should have been issued and sent to every newspaper in the State and from these copied into other newspapers throughoul the country. Tims it was that an entirely erroneous impression was magnified and still further diffused. In older to determine the likelihood that those handling straw in the wheal field will he attacked by the small red mites often mistaken for "chiggers" that abound in the harvested grain at this time, [Cir. 118] 2] Mr. Wildermuth, oi the Bureau of Entomology, made a number of experiments. Tn no case was he able to provoke an attack from these red mites, probablj Tydeus sp., even when the} were confined upon the skin of his bare arm. On the other hand, examinations of straw from various points in Ohio and Indiana have revealed the presenc of Pediculoides in the cells occupied by the jointworm. This seems to entirety eliminate " chiggers" from these investigations because these were probablj nol presenl and there does not longer appear to l>e any doubl thai Pediculoides ventricosus is to be charged with causing the epidemic of this dermatitis. The cause of its nun excessive abundance lies in the outbreaks of the Angoumois grain moth upon the grain in the East and the jointworm in the wheal stra^ in the Middle West. Therefore "chiggers" do not appear to figure as a cause in such epidemics. LIGHT THROWN UPON OTHER PROBLEMS. These investigations have illustrated very nicelj the extent to which the solution <>t' one entomological problem will at the same time also solve other problems more or less closel} allied to the orig- inal one. The light thrown upon the cases of eruption noted by Doctor Harris in connection with the barley jointworm has already been explained. The present outbreak of the jointworm in the Ohio Valley probably originated in the upper Shenandoah Yalle\ of Vir- ginia, extending northward and westward throughout West Virginia and eastern Ohio. When investigation of the insect was taken up in I '.hi i ;, parasite, Ditro'pinotus aureoviridis Crawford, was also noted in excessive abundance, hut for some reason it did not overcome the joint- worm. This phenomenon has been noted continually. Since that time it has been a perpetual enigma to the writer why it was that with such an abundance of its natural enemies the jointworm should con- tinue to spread and increase in dest ruct iveness. Now, however, that we know t hat this predaceous mite is able to develop through a series of years in such immense numbers in connection with the jointworm, the matter comes nearer a solution. Ditropinotus, a- well as some other parasitic enemies of the jointworm, emerge in early Jul} from eggs t hat were previously placed in the cells occupied by the jointworm. As soon as i he adult parasites emerge they at once oviposit in cells con- taining jointworm larvae of the same generation from which they themselves developed. The puncturing of these cells by the ovi- positor of these parasites, particularly Ditropinotus, opens a way for the entrance of this microscopic mite, and, once inside of the cell, it will destroy everything therein, whether it he joint worm or para- site. Thus the predaceous mite has prevented the other parasites from controlling the jointworm because it has continually checked the increase of oi her parasites. [ClP. 118] 22 In the light of the foregoing, it would appear that the only way to evade the disorder among human beings caused by this mite lies in preventing the occurrence of these two destructive grain insects which are responsible for the abundance of the mite itself. There is, therefore, a double incentive for the farmer to use every effort to prevent the occurrence of these pests in his fields. In many fields in Ohio Mr. Wildermuth found that more than one-half of the straws had been attacked by jointworms, and the damage resulting from their attacks amounted to a considerable percentage of the farmers' wheat crop. (See fig. 13.) In addition to this — and we now know that this mite is generally present — his own family and employees suffer the annoyance of this dermatitis and also those who attempt to use mattresses into which the infested straw has en- tered. Thus people hundreds of miles away, unaware of the presence of these mites in mat- tresses, are caused not only great aggravation but intense suffering through their use. DEVELOPMENT OF THE MITES. The investigations carried out during the winter of 1909- 1 9 1 1 >y Mr. Wildermuth reveal the fact that a period of from FIG. 13.— Reduction in yield of wheat attacked by joint- s j x j- Q an indefinite number of worm (Isosoma trilici). The tube at left contains yield ' ' fromliKi heads from uninfested straws; tube at right (lays elapses between the time contains yield from 100 heads from infested straws. female emerges fl'OlU the ab- original.) . ' , ,, ' ,, + -i : + domen of the mother until it produces young. This depends upon temperature. For a temperature of from 90° to 100° F., six days elapses; for a temperature of from 80° to 90° F., seven days elapses; for a temperature of from 70° to 80° F., nine days elapses; for a temperature of from 60° to 70° F., thirteen days elapses, and for a temperature of from 50° to 60° F., twenty-eight days elapses. With temperatures lower than 50° F. it is doubtful if the mites would develop. The periods required for the development of differ- ent females subjected to the same temperature are very uniform. (For instance, in temperatures of from 70° to 80° F. nearly every female produced young in exactly nine days.) The life of the mites [Cir. L18] 23 varied from eighteen to an indefinite number of days forty-three days was the maximum age for those kepi under the lower tempera- tures. The number of young produced by a single female varied considerably and variation was greater among individuals under like conditions than among those under variable conditions. The number varied from jusl a few to 270. From 3 to 8 males were usually | hi m1 need, there being two exceptions to this: Iii one instance, when the temperature was between 70° and 80° F., 26 males were produced and in another case a large number. The firstborn in manj cases were males. The largest number of young produced during any one day by a single female was 52. The ideal temperature for rapid development and the production of the maximum number of young was from 70° to 80° F. The ab- domen of the female reaches its maximum size in about live days. The mite is omnivorous, preferring smooth larva' to hairy ones. A young mite can not enter a closed tsosoma cell. Mites can live onhj a short time without food less than a da\ in all cases observed. Copulation occupies only a feu minutes, the males rarely leaving the surface of the abdomen of their mother. In the laboratory a single Isosoma pupa or larva will sustain a female up to the time she pro- duces young and continue to support her progeny for from twenty to twenty-eight days. In the held, or under natural conditions, one pupa would probably furnish food for live mites for approxi- mately the same length of time, as in one experiment a pupa furnished sufficient food for a month. The miles can be kept alive h\ subject- ing them to a low temperature and development checked for an indefinite time. When attacking human beings they do not bury themselves in the skin and remain there as do the "chiggers." PEEVENTIVE AND PROTECTIVE MEASURES. Throughout the territory involved in the eastern epidemic of this dermatitis, which was due to the excessive abundance of the Ajngou- mois grain moth, the evidence recently obtained by the writer has been overwhelming!) to the effeel thai where wheat was thrashed as promptly as possible alter harvesl and directly from the shocks in the held, almost no occurrence of this grain moth, without which there would be no mites, was observed by millers and others han- dling the thrashed grain. On the other hand, when hauled from the held and placed unthradicd in the bam, the damage from this pes! has varied up to nearly 50 per cent, and has so affected the crop as to can-" it- rejection by millers, except where ground mi the farmer's order. Here, then, is a mean- of protection for people who use or handle wheat straw grown in this section of the country. In Ohio, Indiana, and Illinois, where the mite causing this der- matitis has increased enormously on account of the prevalence of the [CIr. 1 181 24 jointworm, wheat placed in the barn before thrashing has been found much more likely to produce epidemics of this disorder, although the difference between wheat thrashed in the field and in the barn is not so striking as where the trouble results from abundance of the grain moth. A careful study of a large number of wheat fields in central Ohio by the Bureau of Entomology has shown that the infestation from the jointworm during the season of 1909 varied from 1 to 95 per cent. Here, too, the mite was found generally in the cells in the straw occupied by the jointworm larvae. It has been found that in central Ohio September sown wheat is much more seriously affected by the jointworm than that sown in October, and also that the infestation is worse in both cases on poor soil than on that of an average degree of fertility, and still less on good soil. The infestation is invariably worse in fields on which wheat had been grown the previous year, and in fields lying adjacent thereto. Fall-plowed fields showed the least infestation of all. It appears, therefore, that moderately late-sown wheat on good soil and on land not devoted to wheat the previous year nor lying adjacent to such fields, escapes with the least injury, and that less difficulty with the dermatitis is experienced where wheat has been thrashed from the field and as soon as possible after the grain was harvested. As the jointworm winters over in the stub- ble, where this can be burned during fall, winter, or spring, the destruction of both the pest and the mite in the field will be com- plete. Where this can not be done, much good may be accomplished by raking over last year's stubble fields in the spring and burning the stubble thus collected. So important are these measures that practicing physicians might almost include them with their pre- scriptions for this painful skin disorder. SUGGESTION TO CORRESPONDENTS. In order that this mite maybe further studied with reference to its direct relation to man, all requests for information and correspond- ence relating to derniatological matters should be addressed to Dr. Joseph Goldherger, passed assistant surgeon, United States Public Health and Marine-Hospital Service, Hygienic Laboratory, Washington, I). C. All correspondence relating to entomological and agricultural matters connected with epidemics of this skin erup- tion should be addressed to the Bureau of Entomology, Department of Agriculture, Washington, D. C. Approved. James Wilson, Secretary of Agriculture. Washington, D. C, January 11, 1910. [Cir. 118] O UNIVERSITY OF FLORIDA 3 1262 09216 5264