MUSHROOM PESTS AND THEIR CONTROL 



15 



10 to 14 days the larva approaches the surface and spins a fragile 

 silken cocoon, in which it transforms into a pupa (fig. 3, B). In. 

 5 or 6 days the adult fly emerges, and it is capable of mating within] 

 a few hours. Females may commence oviposition within 24 hours. 

 As each female is capable of laying from 200 to 300 eggs, and 

 there is very little natural mortality among the larvae, it will be 

 realized that the potential rate of increase is very great. As a rule, 

 these flies are more common in the mushroom houses in winter than 

 in fall or spring. 



Figure 4. — Eggs of mushroom fly, Sciara fenestrates, 



No effective method* of combating the maggots of these flies within 

 the beds is known. Control must be had through reducing the num- 

 ber of adult flies, thus decreasing the number of eggs laid. Traps 

 and insecticides are the principal means of killing the adult flies. 



TRAPS 



Traps are of many varieties, but they all depend on light to attract 

 the flies to them. They have been used with success, but they should 

 be considered merely supplementary and not be depended on to the 

 exclusion of dusting. The simplest type of trap is a pane of glass 

 set into the south or east end of the house, usually in the door, about 

 a foot or more above the floor. Fly paper or sticky treebanding 

 material is placed about this to catch the flies as they come to the 

 light, or a pan containing a little kerosene may be placed beneath 

 it, into which the flies will fall and be killed. The pane of glass 

 should not be too large, as the ends of the beds will then be too 

 well illuminated and the female flies will often oviposit before they 

 go to the glass, or they will not be attracted to the glass at all. 



