4 FARMERS BULLETIN 789. 



frequently occurring in mushroom 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 of the species should always be made by a specialist. 

 The life history of a mushroom maggot is about as follows: 

 The eggs, of which eacli female is capable of laying nearly 1,000, 

 generally are 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 3 days, but in colder weather 

 this time is considerably extended. Upon hatching, the larvre bore 

 at once into the stem or cap of the mushroom, soon riddling the 

 cap and causing the " breaking down " of the mushroom. On ac- 

 count of the perishable nature of their host 

 they must necessarily pass through their trans- 

 formations quickly. The larvae feed from 7 

 to 10 days, by which time the entire cap is 

 destroyed; the)'^ then enter the ground, each 

 spinning a slight silken cocoon just beneath 

 the surface, and pupate. The pupa stage lasts 

 from 4 to 7 days, after which the insects 

 emerge as adults and soon pair and lay eggs 

 for the next generation. Owing to the im- 

 mense number of eggs deposited and to the 

 FIG. L-A mushroom ^, short life cycle, the rapidity of their increase 

 Aphiochaeta aibidihai- jg remarkable, so that the presence of onlv a 



tcris: Male. Much en- . . . ^, i i i. j.i ^ 



larged. (Author's Hius- few lusccts lu the uiushroom house at the be- 

 tration.) ginning of the season may result in millions 



after the beginning of warm weather, thus effectually preventing 



the cultivation of mushrooms. 



Where it is possible to keep the temperature of the nuishroom 

 house at 55° F. or to reduce it to that temperature upon indications 

 of attack by maggots, damage by these pests is easily controlled. 

 Otherwise it is evident that, in the control of the mushroom maggots, 

 jueasures should be undertaken early in the season for their elimina- 

 tion from the mushroom house and precautions observed against theli- 

 subsequent entrance. These precautions should begin Avith the con- 

 struction of the house or cellar. The building should be so con- 

 structed as to permit of effective fumigation and should be fitted with 

 tight screens of fine wire gauze, suitable to prevent the ingress of 

 the fungus gnats. The gnats may also be brought into the house 

 through the agency of tlie nuinure used in the beds, especially if 

 the compost is carelessly prepared. In large commercial houses the 



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