July, 1914.] THE APPLE MAGGOT. 81 



DURATION OF THE LARVAL STAGE. 



It is clear from much data already noted that the duration of 

 the larval stage with this species is variable, being influenced 

 materially by the variety of apple in which the larva is at work, 

 the condition of the fruit, the time of season, and probably other 

 factors. 



That the larval stage may on occasion be completed in normal 

 surroundings in not to exceed thirty days is suggested by the 

 following: 



In 1911 the date of first emergence of adults recorded at Dur- 

 ham was June 26. The first larva recordes from apples col- 

 lected at Durham issued August 4. Assuming four days as the 

 minimum period after emergence of the adult before egg-laying 

 can begin, and five days as the duration of the egg stage, the 

 length of the larval period would be not to exceed thirty days. 

 That it may be less is obvious. Also it is certain that with hard, 

 winter fruit the stage may last for many weeks longer. 



Harvey (25, p. 202) found newly hatched larvae about July 10 

 in Early Harvests, and found the maggots maturing August 10. 



EXIT OF LARVA FROM FRUIT. 



When growth is completed the larva normally leaves the fruit 

 to prepare for pupation. As already noted this takes place 

 after the fruit has fallen from the tree. A somewhat irregular 

 hole is made through the skin of the apple, and the larva squeezes 

 through this. The hole is not made very large. Occasionally 

 larvae start to force the body through and when half-way out are 

 unable to get farther. Usually the process of issuance is rapidly 

 accomplished. If the larva has not come out at a point near to 

 or in contact with the soil it makes its way over the surface of the 

 fruit, to which it seems able to cHng fairly well. 



After issuing the larva may crawl about on the surface of the 

 soil for some time before entering it. This seemed especially 

 true if the apple from which the larva had issued was removed. 

 Under these conditions larvae were found still uncontracted and 

 on the surface of the ground after nine hours. In one instance 

 the apple was replaced after eight and a half hours, and two 

 larvae that had issued from it at once made their way toward it 

 and in half an hour disappeared. 



