198 THE APPLE 



and with a slightly convex upper surface. When the eggs have 

 attained a certain stage of incubation (variable according to season 

 and temperature) a reddish ring appears around the center, which 

 later changes to a black spot. The egg is then almost ready to 

 hatch. Early in the season eggs require eight or ten days for 

 hatching, but as the season advances fewer days are required, the 

 average being about five days in June, July, and August. 



The larva. From the egg emerges the larva, the length of 

 which is then only about a sixteenth of an inch. It proceeds 

 almost at once to crawl to the nearest apple, sometimes selecting 

 as a site for its entrance an abrasion or break in the skin, but 

 usually the blossom end. It is not uncommon to find the larva 

 first feeding on the leaf, especially when it was hatched some 

 distance from an apple. Most of the invasions of the fruit are 

 effected through the calyces, as these afford the least natural 

 resistance, but the larvae also often penetrate the unbroken skin 

 of the fruit. They usually protect themselves by a network of 

 silken threads spun at the place of entrance. 



The color of the young larva is white at first, but becomes pink- 

 ish as it increases in size. There are three pairs of true legs on 

 the anterior part of the body and five pairs of prolegs on the 

 abdominal segments. 



As the larva feeds, it increases rapidly in size. The castings 

 produced along the journey into the fruit are at first thrust back- 

 wards and out of the opening made by entering. This mass is 

 held together by silken threads. Later, as the larva advances into 

 the apple, generally toward the core, the castings are pushed into 

 the channels which it has traced. Full growth is attained in ap- 

 proximately three weeks (a variable item), and the larva is ready 

 to leave the fruit. When full grown, it measures from | to | inch 

 in length. 



When ready to make its exit from the fruit, it either makes use 

 of the entrance channels or eats its way to liberty at another point. 



When apples are infested before they are half grown or soon 

 after, they generally fall from the tree. Usually, however, the fruit 

 does not fall until after the emergence of the larva. In the latter 

 part of the season most of the infested fruit holds to the tree, but 

 is of greatly lessened value, if not entirely worthless. 



