84 MISCELLANEOUS RESULTS OF WORK OF BUREAU IX. 



HABITS OF THE LARVA. 



The larvae of Coleopliora carysefoliella, upon hatching from the 

 eggs in July, mine the leaves of the host plant, and after feeding there 

 for some time cut out the two skins of the mine and construct the 

 cases within which they live during the fall and winter. After the 

 cases are made the larvae feed upon the leaves by eating through the 

 lower epidermis and tunneling out the interior of the leaf in all 

 directions until the mine is so large that to mine farther the larvae 

 would have to leave their cases. Under such conditions they move 

 and begin a new mine, so that the leaves become full of irregular 

 rectangular patches of brown with a small round hole in the center 

 on the underside. In feeding, the larvae carry the cases nearly 

 perpendicular to the leaf surface. When the larvae move they extend 

 the head and thorax and crawl along, bearing the case aloft behind. 

 In the fall, some time in October, before the leaves fall, these larvse 

 move from the leaves to the twigs or to the trunk, where they get 

 behind the bark. Often they get in between the bud and the twig. 

 Here they fasten the cases to the support and hibernate. The writer 

 has seen from fifteen to twenty minute cases on a twig 4 to 5 inches 

 in length, and where very abundant they will cluster together literally 

 in hundreds. Gossard 7 has a photograph of these winter cases com- 

 pletely covering a twig. 



In the spring, when the weather becomes warm enough, generally 

 between March 15 and April 1, these larvae become active and leave 

 the twigs, where they have spent the winter, to commence feeding. 

 If the trees are backward they often begin to feed before the leaves 

 have developed and in such cases attach themselves to the swelling 

 buds. Each larva eats a minute round hole into a bud and feeds as 

 long as it can reach food without leaving its small case. When this 

 becomes impossible the larva changes position and attacks the bud 

 in a new place, so that infested buds are often found with four or 

 five holes in the sides. Under such treatment the buds are killed or 

 the tiny leaves start and are killed, and turning brown drop off. 

 Often the larvae attack the young tender leaves and mine out rectan- 

 gular blotches in them. About the first week in April these larvae 

 outgrow their winter cases and construct larger ones. 



Larvae forming new cases move to the edge of the leaf and mine 

 between the two skins. They then cut out a portion of the leaf, 

 using the edge for one side. The sides are then sealed with silk, an 

 opening being left at one end for the head. From the method of 

 making new nests one edge of the case will often show serrations of 

 the leaf edge. The larvae then leave the old case attached to the 

 leaf, where the latter has been cut to form a new case. They eat 

 out large mines from 2 to 8 mm. long and 4 to 5 mm. wide (PL V, 



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