34 



out an irregular cavity al)out the core, and seems especially partial 

 to the seeds. 



The insects pass through five larval stages, and increase in size by 

 shedding their skins four times to allow for growth. The width of 

 the head of the larva in these different stages averages as follows: 

 First stage, 0.38 mm.; second stage, 0.55 ram.; third stage, 0.T8 mm.; 

 fourth stage, 1.12 mm.; fifth stage, 1.6 mm. When in the latter part 

 of the first stage and the second part of the third stage the larva? are 

 whitish in color, but with the cervical and anal shields black, and 

 with blackish spots around the set?e. In the later stages the. shields 

 become brown, and the spots around the hairs are usually indistinct, 

 especialh^ in the pinkish larvte. 



TIME SPENT IN THE FRUIT. 



Very few definite obsei'vations have been made in regard to the 

 time the larva spends inside the fruit. Le Baron gave the time as 

 four weeks; Riley, 25 to 30 days; Slingerland, 20 to 30 days; Card, 10 

 to 14 days; and Cordley, 16 to 24 days. From the nature of the case 

 it is most difiicult to get exact data on this point, as there are many 

 accidents which may prove fatal to the experiment. On only 5 larvae 

 was the writer able to obtain results definite enough to use with any 

 degree of confidence. One of these larva; remained in the apple 14 

 da3^s, two 18 days, one 21 da3"s, and another 26 days. Professor Gil- 

 lette kindly furnishes some unpublished data on this point, in which 

 he finds larvae to have stayed in the fruits 12, 18, 20, and 24 daj's, 

 respectively, with an average of 19 days. The average of all these 

 observations is a])out 20 days. 



PREPARATIONS FOR LEAVING THE FRUIT. 



When about full grown the larva makes a passageway to the out- 

 side of the fruit. This is usually made toward the side of the apple, 

 in a difi'erent direction from that from the entrance hole. Rarel}^ 

 does the exit passage follow along or consist of the enlarged entrance 

 passage. Before the larva has passed outside the outer portion of the 

 passage is filled with a block of frnss (PI. V, fig. 2, ((), or a cap of silk is 

 spun over the hole. 



LEAVING THE FRUIT. 



When ready to leave the fruit the larva pushes out this block or 

 tears away the cap of silk, crawls out on the surface of the apple, and 

 immediately seeks a place in which to spin a cocoon. (PI. V, fig. 2, h.) 

 If the apple is upon the tree the larviB will, in by far the greater num- 

 ber of cases, crawl from the apple to the twig, from there to the 

 branch, and thence down upon the trunk of the tree. Another method, 

 which is comparatively rare, is that in which the larva lets itself down 



