TWO INSECTS OF THE ORCHARD SNODGRASS. 501 



When the caterpillar is full grown in this, its third and last stage 

 (pi. 2, /), it reaches a length of 7 millimeters, almost a third of an 

 inch. The body is thickest behind the middle, the skin is naked ex- 

 cept for small hairs distributed over its surface as shown by figure 11. 

 The head and prothoracic shield are brown, the latter with a number 

 of small, dark spots (pi. 2./), the body olive or brownish green with a 

 whitish band along each side and around the front edge of the pro- 

 thoracic shield. The hairs of the body arise mostly from whitish 

 spots on the tops of small swellings. 



The caterpillars of the spring brood reach maturity from the lat- 

 ter part of July to the end of August in southern New England and 

 then construct the ribbed cocoons in which they pupate. Slinger- 

 land and Fletcher state that in southern New York these cocoons are 

 spun during the first half of July, but at Wallingford, Connecticut, 

 the writer first noted fresh cocoons in the orchard on July 19 and 

 saw others spun as late as August 28 and 29. The summer pupal 

 cocoons are spun on the leaves and even on the fruit, p.s well as on 

 the twigs, branches, and trunks, the permanency of the site being 



Fig. 11. — The mature caterpillar of Bucculatrix (enlarged 12 times). 



of little consequence now because at this season the pupal stage is 

 completed in less than two weeks. The moths of this generation 

 emerge during midsummer and lay eggs for a late summer and fall 

 brood of caterpillars. These simply repeat the history of the first 

 brood, but they are generally more numerous, and the damage from 

 their feeding becomes particularly noticeable by early fall. The 

 first to mature in southern New England spin their cocoons dur- 

 ing the early part of September while others feed till almost the 

 end of October. As the cocooning time for each approaches, the 

 caterpillar becomes restless, leaves its feeding grounds, explores the 

 tree from the end of a thread, and travels about over the branches 

 till it finds a suitable place for its winter quarters. Though the 

 trees are still full of leaves and fruit, instinct this time tells the 

 caterpillars that safety for the winter is to be found only on the 

 more permanent parts of the tree. Consequently almost all the 

 cocoons spun at this season are on the twigs, branches, or trunks, 

 though an occasional careless or misguided individual builds its 

 house on a leaf. The structure of the cocoon is the same whether 

 built for the brief summer occupancy or for the long period of 

 hibernation between October and May. 



