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CIRCULAR 4 5 7, U. S. DEPARTMENT OF AGRICULTURE 



Flies attacking cultivated mushrooms are of three general kinds, 

 known as mushroom flies or fungus gnats, manure flies, and ceci- 

 domyiid flies. All these are normally scavengers, feeding on wild 

 fungi, leaf mold, and other organic material, and are not unduly nu- 

 merous. With the concentration of their natural food, however, as in 

 a mushroom house, they are able to build up abnormal populations. 



MUSHROOM FLIES OR FUNGUS GNATS 



There are at least four species of sciarid flies (of the genus Sciara) 

 that have been recorded as injuring cultivated mushrooms seriously 



in the United States. 

 Probably the most 

 common of these is 

 S. fenestralis Zett. 

 Others that have 

 been noted as attack- 

 ing mushrooms are 

 S. coprophila Lint- 

 ner, S. multiseta Felt, 

 and S. agraria Felt. 

 They are much alike 

 in appearance, habits, 

 and life history, and 

 for practical pur- 

 poses may be re- 

 garded as one species. 

 Figure 3, c 7 , shows a 

 drawing of an adult 

 fly. Sciarid flies are 

 slender, with rather 

 long legs and an- 

 tennae. They usual- 

 ly carry their wings 

 folded flat upon the 

 back when walking 

 or at rest. They are 

 black or yellow black. 

 The males have a 

 pair of claspers at the 

 apex of the abdomen. 

 The eggs (fig. 4) 

 of these flies are very 

 small, oval, white or 

 yellowish. They are 

 laid in the compost 

 or spawn, in cracks 

 in the casing soil, or 

 upon the mushrooms. 

 Under favorable con- 

 ditions of tempera- 

 ture and humidity 

 the egg hatches in 4 or 5 days into a legless white larva, or mag- 

 got, with a shiny, black head (fig. 3, J.). After feeding for from 



Figure 3. — Stages of a 

 trails: A, larva, X 10: 

 C, adult, X 12. 



mushroom fly, Sciara 

 B, pupa, ventral view, 



fenes- 

 X 15: 



