-. -> ; / -> T r. S. DEPARTMENT OF AGRICULTURE, BUREAU OF ENTOMOLOGY-CIRCULAR No. 155. L. O. HOWARD. Fnlomologisl tnd Chirf of Bureau. INSECTS INJURIOUS TO MUSHROOMS. BY C. II. POPEXOE, Entomological Attiita nt. WASHINGTON : GOVERNMENT PRINTING OFFICE : 1t12 BUREAU OF EXTOUOLOGY. L. O. Howard, Entomologist and Chief of Bureau. C. L. Marlatt, Entomologist and Acting Chief in Absence of Chief. R. S. Clifton, Executive Assistant. W. F. Tastet, Chief Clerk. F. H. Chittenden, in < harge of truck crop and stored product insect investigations. 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 incest igat ions. A. L. Quaintance, in charge of deciduous fruit insect investigations. E. F. Phillips, in charge of bee culture. I). M. Rogers, in charge of preventing spread of moths, field work. Bulla I'. Currie, in charge of editorial work. Mabel Colcord, in charge of library. Truck Crop and Stored Product Insect Investigations. F. II. Chittenden, in charge. II. M. Russell, C. II. Fopenoe, William B. Parker. II. O. Marsh, M. M. High, Fred A. Johnston, John E. Gkae. entomological assistants. I. J. Condit. collaborator in California. W. X. Obd, collaborator in On gnu. Thomas II. Jones, collaborator in Porto Rico. Marion T. Van Horn, Pauline M. Johnson, Anita M. Ballinger, preparators. Circular No. 155. L91Z United States Department of Agriculture, BUREAU OP ENTOMOLOGY. L. O. HOWARD, EntomoloRist .in.l Chief of Bureau. INSECTS IN.M IMOI s TO MUSHROOMS. By C. ll l'l'ii hoi . Entomological I ssistant. Cultivated mushrooms, especially during warm weather, are at- tacked by several species of insect pests which frequently destroy an entire crop, or so curtail tin- production as to make the industry unprofitable. Although this injury is al times serious, little interesl has been taken by entomologists in the matter of it- i trol, so that there is practically n<> available economic literature on the subject. This circular is of a preliminary nature, as the investigation of all insects injurious to mushrooms may not be completed for some time. .' insects which usually attack culti- vated mushrooms, and those of which com- plaints are most frequently made, ma\ divided roughly into four classes, namely, mushroom maggots, mites, springtails, and ' ' ihroom fly. ApM- i .1.1 '" ' sowbugs. Ol these the maggots are the M mosl generally injurious, the mites follow in order of importance, owing to the difficulty with which their eradication is accomplished, and then come springtails and sowbugs in the order named. MUSHROOM MAGGOTS. Bra militia ta Fell el bL) The injurious forms commonly known as "mushroom maggots" are small whitish or yellowish-white maggots usually having black head-. fir. 156— 12 1 2 INSECTS INJURIOUS TO MUSHROOMS. They are the young of certain small flies or "gnats,*' two-winged and mostly black in color, of several species belonging to the fami- lies Mycetopbilidae and Phoridse, and to the genera Sciara and Aphiochaeta. Of these the species belonging to the genus Sciara are by far the most common and injurious of mushroom pests. They are minute in size, measuring about three thirty-seconds of an inch in length and about one-eighth inch in spread of wings. They are smoky or dusty black in color. The species attracting most atten- tion as pests are Sciara multiseta Felt and Sciara agraria Felt. Both species are, like the other mushroom gnats, rapid and prolific breed- ers, especially during warm weather, frequently occurring in mush- room houses so abundantly as to darken the windows. They may be readily confused, however, with gnats of the same genus which breed in manure or in greenhouse soil, and determinations should always be made by a specialist. Another common species, Aphiochceta albidihalteris Felt (fig. 1), superficially resembles the preceding, and has much the same habits, but as yet has not appeared to cause so much damage as have the species before mentioned. The life history of one of the mushroom maggots is about as fol- lows : The eggs, of which each female is capable of laying nearly 1,000, are generally deposited at the juncture of the stem and cap of the mushroom, or in the manure or soil at its base. In a warm tem- perature they may hatch within three days, but in colder weather this time may be considerably extended. Upon hatching the larva? bore at once into the stem or cap of the mushroom, soon riddling the cap, and causing the breaking down of the mushroom in a short time. On account of the perishable nature of their host they pass through their transformations quickly, the larvae feeding for from 7 to 10 days, by which time the entire cap is destroyed. The larva 1 then enter the ground, each spinning a slight silken cocoon just beneath the surface, and pupating. The pupa stage lasts from four to seven clays, after which the insects emerge as adults, soon afterwards pairing and ovipositing for the next generation. Owing to the immense number of eggs deposited and to the short life-cycle the rapidity of their increase is remarkable, so that the presence of only a few insects in the mushroom house at the beginning of the season may result in the presence of millions after the beginning of warm weather, thus effectually preventing the cultivation of mushrooms. CONTROL. It is evident that in the control of the mushroom maggots measures should be undertaken early in the season for their elimination from the mushroom house and precautions observed against their subse- , fS l\ i i RIOl - i" Mi 3HROOM8. ([ ,i,.iit entrance. These should begin with th< iction of the house or cellar. The building should be so constructed as to |>< of effective fumigation and should befitted with tighl screens of fine wire gauze, suitable to prevent tl i the fui \i The gnats may also be brought into the house through the agency of the manure used in the compost beds, so thai it is well to disinfect or sterilize this substance by means of steam. This maj be accomplished by placing tin- manure or soil in vats or boxes, through which -tram pipe-, perforated to allow the escape of the steam into the boxes, are conducted. I See fig. 2. » The manure should be heated to a tern l ur€ f iso I'., which will destroy all animal life occurring thereii. without injury to its capacity for producing mushrooms. Fumiga Hon with bisulphid of carbon just prei ious to planting the mushrooms i> also productive of good results in destroying maggots in the com- post. The bisulphid should Ik- used at a strength of 2 to t pounds to 1,000 cubic feet of ^— y and should be evaporated in shallow pans placed in the highest part of thf house. It is wry inflammable ami even explosive when brought into i contact with lift* or sparks, so that care should be used to avoid bringing any fire into the building during the process of fumigation. One of the besl methods for the destruction of the adults or ili<'~ in their occurrence in mushroom houses is fumigation with tobacco or nicotine fumigants such as are used in greenhouses. I hese should be used in accordance with the directions indicated on the package for ■ medium or heavy fumigation. 1 Used in this manner, and ap- plied once a week during the bearing season of the mushroom bed. thi> method has been so successful in reducing the number of flies that very little damage, if any. resulted from the larva-. Fumination with pyTethrum of dusting the powder over the beds is also effective against the mushroom maggots if taken in time, but tobacco fumigation mav be considered standard for this use. 2. Si -a in in ,\. or rtei > ;i [ i nm- « The proportion of nicotine in the several pi Dl «iiat odard dose lin< n< yel been formulated. INSECTS INJURIOUS TO MUSHROOMS. THE MUSHROOM MITE. (Tyroglyphus lintneri Osb.) The mushroom mite (Tyroglyphus lintneri Osb.) (fig. 3) is a minute, soft-bodied mite, smooth skinned, and white or whitish in color. It is closely allied to the common cheese mite (Tyroylyphus siro L.) and resembles that species in appearance. It is, if anything:, more prolific than the cheese mite, becoming at times so abundant in mushroom beds as to cover the surface of the compost, and when present in such numbers is extremely destructive, feeding upon the mushrooms in all stages and penetrating the beds and destroying the mycelium. Indeed, in one case observet 1 by Mr. August Busck, of this bureau. 1 the mycelium was destroyed as fast as it grew from the spawn. This species is undoubtedly the cause in many cases of the failure of the spawn to grow, which is likely to be attributed to poor or weak spawn, or to defective cultural conditions. The minute size of the mites causes their presence to be little suspected, and the failure of the spawn to produce mycelium is not understood. Even under conditions favorable to* the growth of the mycelium it is possible for the mites to increase to such an extent that the en- tire bed may be killed out. Besides the injury to the my- celium, mushroom mites cause damage to the fruiting bodies by eating into them, distorting or destroying the young growth. In the more mature mushrooms the mites may be found clustered in groups consisting of individuals of many sizes, usually hidden in the folds between the gills, where they burrow into the tissue and rapidly break down the cap-. No direct observations bearing on the life history of this species have been made, but judging from that of related species it is about as follows: The eggs, which are huge in proportion to the size of the mites, are laid in or about the mycelium of the mushroom, or on the PlG. ". — The mushroom mite (Tiiroijlyphus lintneri). Highly magnified. (From Banks, i Uiul. 38, Bar. Ent., V. ». Dept Agr., 1904. i ' rs IN. I l RI01 a l<> Mi BHBOOM8. 5 young or developing cap& Thej hatch in a Bhort tim< into il bar- ;n teristic six legged young, which rapidly mature to adults similar t<> the one in figure 2. The time from t In- deposition of the egg t«» 1 1 * « - maturity of the mite has not, to the writer's knowledge, been accu- rate]} worked out. I>ut undoubtedly occupies onlj a l'«u days, li is on this account that the mite is able i<> increase bo rapidly, apparently l* by magic, and thus give rise to the theory of spontaneous genera- tion sometimes advanced to explain this condition. Dnder certain conditions the hypopus < >r migrator) stage is pro- duced. This stage, according to Banks, 1 is peculiar i<> the family Tyroglyphidse, to which this mite belongs, ami is quite remarkable. The mite develops a hard, chitinous covering, has m> mouthparts, and i- provided with short legs insufficient for walking. On the ventral sin- face of the body is an area provided with Bucking disks, by means of which the hypopus attaches itself to an insect and is so transported to suitable breeding grounds in other localities. On arrival at a suit- able breeding place the mite detaches itself from its insect host, molts, and soon becomes adult. During the hypopus stage the mite take- no food and causes no injury to the insect which carries it. This peculiar stage is the natural means t'<>r the distribution of the mite to new localities, and is in many cases responsible for it- appearance in localities far from previously infested beds. In addition to the way mentioned above, the mite may obtain access to mushroom houses in infested compost or in spawn from infested houses. However, the greater part of the infestation prob- ably takes place through the agency of the small flies which frequent mushroom houses and which carry the hypopus stage of the mite from one house to another. R] Ml mi a. Little can be recommended for the control of the mushroom mite after it has once become established in a house. Owing to the al>- Bence of breathing-pores it is little affected by the fumigants suitable for the control of the other mushroom pests, while applications of sulphur, tobacco dust, and other suitable insecticides to the beds Beem only to prove slightly inconvenient to the mite. It i- one of the most stubborn pests with which we have to deal in mushroom culture, and may be brought into the house in almost any manure that is used for the bed. When in the hypopus stage it is capable of prolonged suspension of vitality and is likely to remain in the house for an unlimited time without death. The only measures, there!*, that may be considered are those of prevention. When a house becomes infested, all compost should be gathered with the utmost care, remove.] to the outside, and thoroughly disin- 1 Pro.-. 1". s. Nat Mm., wl. 28, p 7'.'. 1904. 6 INSECTS INJURIOUS TO MUSHROOMS. fected by drenching with boiling water, or it may be hauled to a dis- tance and spread upon the ground as fertilizer, or it may be destroyed Ivy burning. The ground occupied by the mushroom beds should be thoroughly scalded, and the woodwork of the mushroom house treated (o a wash of creosote or crude carbolic acid, either of which is distaste- ful to the mites. After complete disinfection has been accomplished the house should be screened, to guard against subsequent introduction of the pest by means of flics. All manure forming the beds should be steamed, according to the directions under the head of mushroom maggots. Care should be used to purchase spawn only from unin- fected houses. "With these precautions it is unlikely that trouble will be experienced from the attacks of the mushroom mite. Close watch should be kept, however, for any signs of the presence of the mites in the beds, and the compost destroyed upon their first appearance, as it is impossible to secure good results with mushrooms when in- fested by these mites. All applications of suffi- cient strength to destroy the mites are likewise injurious to the mushrooms, and it is futile to attempt to control by any artificial means, once the mushroom bed becomes infested, as the miles are buried so deeply in the compost that no insec- ticide will reach them. A predaceous mite belonging to the Gamasidae frequently occurs in beds infested by the mush- room mite, feeding upon the latter, and at times """".""V n , becoming so numerous as entirely to wipe out the j u no us springtsul, = _ . Achoreutea arm a- pest. The gamasid may be known by its longer turn. Miicii en- j j - { manner f running swiftly over the largcd. (Original. I *= . compost or the mushrooms. The writer has seen cases where the gamasid has occurred in such abundance as greatly to outnumber its host. This predaceous enemy does not feed on the mushrooms after the destruction of the mites, but seeks other feeding grounds, or dies by starvation. SPRINGTAILS. {Achoreutes armatum Nicolet et al.) At times the surface of a mushroom bed becomes alive with minute brown or black insects, which, when disturbed, leap about like fleas in an extremely erratic manner. These are known as springtaiLs, since the springing is performed by the aid of two short bristles situated on the anal >egment of the abdomen. These insects (Acho- reutes armatum,, see fig. 4) are present in almost all manure, where they feed on the decaying vegetation present, but on occasion they may Income quite injurious in mushroom houses. A correspondent 3 IN i QRI0U8 i" M CT8B ROOMS. 7 iii St. Louis, Mo., reported that in one "f his mushroom houses m l>cl L60 feet in length had been completely destroyed by these pests, which attacked the mushrooms as fast a they appeared, honey-combing tin-in and rendering them until fur use. The method of attack of this insect is to feed upon the fruiting bodies of tin- mushrooms, roying both tin- gills and the cap. Hundreds ma\ be found clustered upon ;i single mushroom and eating large cavities in the gills. Ii appears to he ;i habit <•(' these insects t<> cot in large numbers <>n caps which have been slightly injured, in which they rapidly destroy mushrooms which would be readily salable if tin- injury were not continued. When they occur in large numbers they an- likely to attack even the perfect mushrooms, in aL r L r ra\ateil cases destroying whole beds. Insects <>f this group pass through n<> larval transformation, tin' form of the newly hatched young being similar to that of the adult. They are thus likely t<> be injurious in the same manner throughout their life history. i;i Mi nil S. The remedial measures applicable t" the control of springtails are i.' i large extent preventive, a- these insects are somewhat difficult ntrol when once established in a mushroom bed. They are quite tan! to tobacco powders, but applications of buhach or pyreth- rmn to the beds are productive of -nine good. A- they usually con- gregate near the surface of the beds fumigation with hydrocy acid gas, according to the directions given in Circular -7 of this bureau, will prove effective in reducing their numbers. The cyanid should be used at a strength of from 3 i" 6 ounces to each 1,000 cubic of air space, which will not prove injurious to the mycelium. By way of prevention, steaming all manure, a- previously sug- gested for other species, will destroy springtails equally well. Where ble, it is better to grow the mushrooms at a temperature of about I". than higher, a- at low temperatures the springtails breed much less quickly. Dusting the top- of the beds with powdered lime is also said to discourage attack by springfa SOWBUGS. i Irmadillidium spp. anil PorceUio 9pp.) Considerable injury is often accomplished to mushroom beds through the attacks ( >f oval, grayish, or slate-colored creature- bear- ing seven pair- of legs. These creature- are not true insects, although known variously by the term- "woodlice," sowbugs, and "pillbugs.' 1 Two . the greenhouse pillbug {Armadillidium vulgan La- 8 INSECTS INJURIOUS TO MUSHROOMS. treille) and the dooryard sowbug (PorceUio hi vis Koch), are illus- trated in figures 5, 6, and 7. Sowbugs live in damp, dark places, such as beneath boards, in cellars, and in the cracks of sidewalks. When disturbed many spe- cies roll up to form a ball, lying quite still until the danger is past. (See fig. 5.) During the night they issue from their hiding places to feed upon decaying vege- table matter, molds, and other material present in damp soils, although at times the roots of plants and even the green leaves are not es- chewed. The young are carried about in a pouch, formed by several modified anal plates on the abdomen of the female, until able to shift for themselves. "When released by the female the young are similar in appearance to the adults, although much smaller, and are likewise cap- able of damage. There is probably only one generation annually, the young making their ap- pearance in the spring and requiring one sum- mer to reach maturity. The destruction occasioned hj sowbug- is due to their attacks on the caps or fruiting bodies of the mushrooms. These they attack while quite small, destroying them or injur- ing their appearance. T\\zx do not, as a rule, attack the mycelium, but eat holes in the young " buttons, which, on the completion of the growth, become much larger and disfigure the product. Sowbugs are, more frequently than at first might be thought, carried into the mushroom house in compost which has been allowed to stand outside. The heat of the manure is relished by them, and they collect in numbers. Fig. 5. — The greenhouse pi 11 bug (ArmniliUitliina vulgare) extended. Much enlarged. (Orig- inal.) Fig. 6. — The greenhouse pillbug {Armadilliilium vulgare) contracted. Much enlarged. (Orig- inal.) Fig. 7. — Dooryard sowbug (Porcellio Iwvis). Much enlarged. (Original.) remaining there throughout the growth of the spawn, but becoming injurious with the first growth of the mushrooms. The writer has seen sowbugs collected in manure piles to such an extent that numbers aggregating a pint or more in quantity might have been collected from a shovelful of material. INSECTS I n.i URI01 a ro M I >il ROOMS. 1:1 \u i. ii -. \\ here 1 1 u> mushroom house i- small in extenl ii is possible materi- ally to reduce the numbers of sowbugs bj means of hand picking. The house may be visited at night, when, l>\ the aid of a lantern, Dumbers of sowbugs may be seen crawling about on the earthen casing of the beds and upon the boards and supports of the benches. These may be destroyed with a small wooden paddle. It is also possible to secure good results by pouring hoi water along the cracks in the boards and in other places where the "bugs" may be concealed by day. This is effective in small establishments, but is Bomewhat difficult <>i' application in large houses. In such a fumigation with hydrocyanic-acid gas is an effective remedy. Treat- ment with sulphur dioxid' is also effective, but this remedy should be applied after the mushroom crop has been harvested and the com- post has been removed. Another method i- to cut small pieces of raw potato, plastering the wet surface with Paris green, and laying them about on the beds in the localities affected by the sowbugs. This method is frequently successful in entirely ridding houses of this pest. CRICKETS. Among other injurious form- which a! times attack mushrooms, certain cricket- are reported as eating into the caps of the mush- rooms, (hi the Pacific coast a species known scientifically as Ceu- thophilus pacificiu Thorn, has been reported as causing extensive injury to cultivated mushroom beds. The remedies for cricket- in their injurious occurrence are the same a> those recommended for sowbugs in a previous section of this circular. Potatoes and carrot- may he minced before applying the Paris green, in order to secure a somewhat thicker coat. GENERAL SUMMARY. In the construction of mushroom houses care should he taken to make the building a- tight a- possible and with few- outlets. If window- are necessary they should he -mall and should be screened with fine wire gauze, which form- an excellent prevention against the entrance of both maggots and mite-, a- previously mentioned. If possible all compost should be steamed before being placed in the house and the temperature should he kept below 55 I - "., as all insects are more or less dormant at this temperature, and their otherwise reprint from BaL 6". Bur. KM., l 6 Icolrore, pp. ' - ilphtir Dioxid as an Insecticide. 10 INSECTS INJURIOUS TO MUSIIP.dn M B. rapid multiplication is thereby greatly checked, reducing infestation to a minimum. If these recommendations are carefully followed there should be little necessity for the radical measures of fumigation or destruction of the beds. Approved: James Wilson, Secretary of Agriculture. Washington, D. C, April 17, 1912. ADDITIONAL COPIES of this publication S\- may be procured from the Superintend- ent of Documents, Government Printing Office, Washington, D. C. , at 5 cents per copy UNIVERSITY OF FLORIDA 3 1262 09216 5645 !