208 THE APPLE 



are marked differences in infestation in different seasons ; and 

 (4) that it is difficult to control. 



The maggot that does the injury is the larvae of a two-winged fly, 

 a little smaller than the house fly. At the North the flies appear 

 early in July ; in more southern regions somewhat earlier. The 

 eggs are deposited singly beneath the skin of the apple. An indi- 

 vidual female is capable of producing from 300 to 400 eggs, the 

 period of egg-laying continuing throughout its life. The larvae bore 

 irregular channels through the fruit, feeding as they go. The feed- 

 ing period continues until the fruit drops and becomes mellow. 

 Then the larvae bore out, go below the ground surface to pupate, 

 and there remain as pupae until time for the flies to emerge in 

 early summer. There is thus but one brood a year. 



As the eggs are deposited under the skin of the fruit and the 

 larvae feed entirely within, applications of poison are ineffective. 

 There are two remedial measures that are successful in proportion 

 to the thoroughness with which they are performed ; namely, de- 

 struction of the fallen fruit and frequent tillage of the surface soil. 

 The first aims at the destruction of the larvae, the second is more 

 or less destructive to the pupae. 



