196 BULLETIN NO. 62. 



tablished by actual observations. The importance of the question 

 lies in the influence it may have on the effectiveness of arsenical 

 sprays. 



THE LARVA ENTERING THE FRUIT. 



The larva seems to find dififlculty in gaining entrance through the 

 smooth exposed skin of the apple. With the small v^eak jaws it is 

 unable to break through without some advantage of position or aid 

 through a roughened spot. A leaf is sometimes fastened to the 

 side of the apple and from between the two, a small patch of skin is 

 gnawed away. At times the point where two apples touch each 

 other is selected. Wherever the young larva crawls it spins a web 

 which furnishes a footing l)y which it adheres to the apple and is 

 aided in gnawing the skin. At the calyx end of an}^ apple, however 

 exposed, a favorable point oi entrance is furnished in the small pro- 

 tected cavity under the calyx lobes where the skin is thin ; and it 

 is not strange that a large percentage of the larvae, particularly of 

 the first generation, enter at this point. 



The larvae of the second generation are known to enter for the 

 most part on the sides of the apple spinning a web at the point 

 where they intend to enter. Some irregular or roughened place is 

 preferred. 



It has been observed that in biting out small bits of the skin 

 none are eaten. The larva has been seen to actually back out of the 

 partly formed burrows in order to deposit on the surface bits of ap- 

 ple taken from just below. When the larva has finally gnawed in- 

 to the apple it turns about and spins a silken web over the opening. 

 In view of these facts it is not clear how the fatal dose of poison on 

 sprayed fruit is taken into the system. 



As above stated the larvae of the first brood enter principally 

 by way of the calyx cup. In Montana the calyx cup has closed 

 long before the larvae are hatched and it is necessary for them to 

 work their way through between the closed lobes or by boring a 

 small hole through the base of a lobe. Careful investigations by 

 Slingerland, Gillette, and others have shown that as a rule about 

 80 per cent of the first brood enter the fruit in this way. The other 

 20 per cent go in at the side or at the base of the stem. By far a 

 greater part of the second generation enter by the side of the apple. 



