J /ATS L^ V. s DEPAR \WY.\ X I »l \< iRICI I I I l< I 0MOLOG1 No. 158. I O. H< W ARD, Kninmologitt and Chirf ol Bufe.ii. TIIK CLOVER MITE 1". M. WEBSTER, In < Tuargt of Ctr r IRS— 12 .OVESKMENT • BUREAU OF ENTOMOLOGY. 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 charge of truck crop and stared product insi ct investigations. A. D. Hopkins, in charge of forest insect investigations. W. I>. Hunteb, in charge of southern field crop insect investigations. F. M. Websteb, in charge of cereal and foragt insect investigations. A. L. Qtjaintance, i/n charge of deciduous fruit insect investigations. E. F. Phillips, in charge of bee culture. D. M. Rogers, i/n charge of preventing spread of moths, field work. Roll.v P. Currie, in charge of editorial work. Mabel Colcord, in charge of library. Cereal and Fobage Insect Investigations. F. M. Webster, /"// charge. Geo. I. Reeves, VT. J. Phillips. C. N. Ainslie. E. O. (J. Kelly. T. D Crbahns, Harry S. Smith, Geo. <;. Ainslie. .1. A. Hyslop, W. II. Walton. J. T. Monell, J. J. Davis, T. H. Parks, R. A. Vickery. V. L. Wii.permvtii. E. <;. Smyth, Herbert T. Osborn, Philip Luginbill, C. W. C-BfcEL, E. J. Vosler. R. N. Wil- son, Vebnon King, George R. Smith, Irving Crawford, entomological as- sistants. Nettie S. Klopeer. Ellen Dashiell, preparators. Miriam Welles Reeves, collaborator. u Circular No. 158. . United States Department of Agriculture, BUREAU OK ENTOMOLOGY. L. O. HOWARD, Entomologist .ml Chid «.f Hurenu. THE CLOTEB Mill.. yobia prat i n*h < iarman. > By r. M w i B8i In Cha real 'iinl Foraffi Insect Investigations. [NTHOD1 I HON. The minute organism known ;i- the clover mite (fig. Ii is : • true insect, but belongs, with the spiders, to a rery extensive group the adults of which possess eight legs, whereas true in- sects have only six legs. There are a greal many species of these mite- and they differ widely among themselves in habits. Sonic make galls on the leaves of trees and shrubs : some, like the one which commonly at- tacks the currant, arc known as blister mites, as they cause blisters on leave-: others are para-it ic on man. as the itch mite; while -till others, like the Trombidium, arc parasitic on insects. Another. P< dit uloid< s >•• n- Nev p., is parasitic on insects hut also attack- man. The one here treated lives on the surface of leave.- of trees and plant-. but does not cause galls or blisters. It is a near relative of the notorious red spider. The clover mite, also known a- the brown mile, i- of a twofold interest It attack.- the leave.- of clover, grasses, and fruit and other 1 i. — The clover ml Enlarcod : minimi size shown by line at ri^-ht. Z THE CLOVER MITE. trees, feeding upon and often destroying (hem; beside-, during- winter and spring it frequently swarms in dwellings, often crawling about in myriads over windows, furniture, picture-, curtains, etc. The species was first described in 1885. 1 but it was observed in great abundance about Washington, D. C. by Mr. Theodore Pergande, of the Bureau of Entomology, as early as 1878. While described as a clover-infesting species, having been found infesting clover leaves by both Mr. Pergande and Prof. IT. Garman, yet taken as a whole throughout its known area of distribution it is probably of more im- portance to the fruit grower than it is to the farmer. While east of the semiarid region it is found largely on clover and bluegrass, it is at present largely an orchard pest west of about longitude 100°. Fig. 2. — Map showing the distribution of the clover mite {Bryobia pratensis) in the United States in 1911. (Original! DISTRIBUTION. With the possible exception of Georgia the pest seems to occur generally over the whole country, except perhaps in the Gulf States and the Dakotas, though just why it should not be found even there can not now be explained. (See map, fig. 2.) Mr. Marlatt 2 states that it has been reported from Tennessee, and in the Sierra Nevada Mountains in California and Rocky Mountains in Montana at ele- vations of from 7.000 to 8.000 feet, but exact localities are not given. The mite was described from the leaves of red clover (Trifolium pratense) from which it derives its last or specific name. Accom- 1 Fourteenth Rept St. Ent. 111., pp. 73-74, 1885. 2 Cir. 19, Div. Ent., U. S. Dept. Agr., 1897. rHE CLOVER MITE. .'{ panying the original description is the following note b\ Dr. S. \. Forbes, State entomologisl of Qlinois: ai Normal, ea May, the general occurrence 'i conapli brownish red ■■ ■ i i •- was noticed upon clover and bluegrass the former "i" these plants, especially, sometlmef Buffering Beverelj from the peal The lea i the clover turned yellow and their growth w ed where the mite wai ■bandant I'be effecl upon the blues. similar. \- a matter of fact, the bureau records contain reports of the occurrence "I" the species over the territory indicated by the map (fig. •_'). These records illustrate its great varietj of food plant- a- well as th«' effect of climatic and other natural conditions upon its habits; they are, however, far too voluminous to include in a publi- cation of the nature of this circular. Dl B< RIPTION8. These mites are sufficiently shown in figure 1 to obviate the n< -itv for a lengthy description. When young thej are of a decidedly red color, but become brown when fulh developed, even then being smaller than the head of a pin. They are very familiar objects moving about over clover leaves that have a more or less whitish appearance. The discoloration of the leaves is in part due to the feeding of the mitt'-, and also to tin' tiny white web that they leave behind them a- the\ move about. The eggs are minute, round, red, and shining. FOOD PLAN IS. From the foregoing it will be observed that this mite i- ;i | feeder and may be expected to attack clover-, alfalfa, bluegrass, and probably other grasses, among them timothy. It may affect oats and probably other grains including buckwheat. Mr. •( cold weather in late ' i •■ dt «Bul. 162 jr. Coll. Exp. Sta.. p. 6. 1909. 4 THE CLOVBB BUTE. autumn or early winter the mites apparently cease to deposit egg-. and thus operations are simply suspended until the coming of warm weather in spring, when the eggs promptly hatch young mites. This is clearly shown by the observations of Mr. Pergande. A- will be observed, the presence of mies in dwellings during fall and spring is of common occurrence. Do they deposit eggs and do these eggs hatch there { It may be stated thai both eggs and mite were received from "Williainsport. Pa.. December 11. 180G, and that the eggs hatched en route. Also, as observed by the writer, the mite- entering a dwelling in Lafayette. Ind.. during December. 1880, when the weather was very mild, were at first full grown, but young appeared later in the month. Whether nates seek out dwellings in which to continue reproduction but die out for lack of food, or whether they enter them for the purpose of hibernation, is not clear. It is very clear, however, that they do not go into hibernation in May. a time when their occurrence in dwelling- is of equally common occurrence. Furthermore, our notes show that complaints of these mites entering dwellings almost invariably come from the eastern and cooler sections of the country, the reports from McCook, Xebr., and Denver, Colo., being the only exceptions in the West. Mr. George P. Weldon. who studied the species in Colorado. 1 states that it winters there principally in the egg stage and that practically no living mites can be found abroad after August 1. Hatching begins about May 1. and there are probably three generations annually in that region. REMEDIAL AXD PREVENTIVE MEASURES. Tobacco preparations applied in the form of a liquid spray are quite effective in destroying the mite, but do not destroy the egg, and therefore offer only temporary relief. Mr. Weldon found that flowers of sulphur dusted on foliage during early morning was more effective in destroying the mites. A liquid spray of 1 pound flowers of sulphur mixed in -1 gallons of weak soapsuds, 1 pound of soap to 100 gallons of water, was very effective and ap- peared to be lasting in its effects. This last can be easily applied to lawn-- and grounds where the mites are at work and also in field- of clover or alfalfa in case the depredations are confined to -mall spots or areas. The eggs can be destroyed on the trunks of trees by the use of strong kerosene emulsion. The writer has re- ceived reports of good results in driving the mites away from dwell- ings by placing oil of pennyroyal in small shallow dishes in the looms where the mites occur. This measure does away with the disagreeable feature of fumigation with fumes of sulphur or dust- ing with insect powder, and the odor of the oil is not disagreeable to people using the rooms. 1 Loc. cit., p. 3, October. 1909. Till ii i>\ I i; Ml I 1 . O s \ i i 1: m i \ l \i II S. The insect enemies "l" ilii- mite, o far as recorded, are eerj few. ( tetober 28, L889, Mi. Perg md< reared one of the common clothes moths (Tineola hiseUiella Hiibn.) from small caterpillars that be had observed to feed upon tl Mr. Weldon ' gives as enemies "f the red pider (Tetranychtu h'nini< uliit'ts Harv.) a minute black lady-beetle, Scymnu* punctum Lee. MiL r - 3) and lace-winged flies. \- there are many speci< * O IT.. '■ S "riiMu.« punctum, a laih beetle enemy of the clover mlt' Bgg; ''• larva; e, papa; •'. adult. All n . '. ■ . Red iwn fr..m Weldon: <'. original. the Scymnus and of lace-winged flies, ii is nol at all unlikely that some of them prey upon the clover mite. A.pproi ill : James Wn i y of . \>i> icvltun . Washington, D. ( .. April 18, 1912. ADDITIONAL CI IPIES oftl I* pool . I ent or D Offic - copy UNIVERSITY OF FLORIDA 1 1 ii linn in it 3 1262 09216 5942 1