l6 NEW YORK STATE MUSEUM 



the latter part of May in this latitude. They feed at first on the 

 more tender lower epidermis of the leaf and soon devour all but 

 the principal veins. The small caterpillars frequently hang 

 by a silken thread and continued jarring may cause many 

 to drop to the ground. "Feeding and growth occupy a month or 

 more, pupation occurring the latter part of June or early in July. 

 There is some deviation from this, as a few individuals spin up 

 early and some caterpillars linger till numerous egg clusters indi- 

 cate that most of the insects have completed the round of life. 

 The pupal stage occupies from ten to fifteen days. The wingless 

 female appears at the end of this period, crawls on her co- 

 coon and shortly deposits eggs as described. There is normally 

 but one generation annually in Albany and other inland cities, 

 while in New York City and vicinity and in Boston, Mass., there 

 are two broods and at Washington, D. C., there are three gen- 

 erations each year as stated by Doctor Howard. 



The young caterpillars drop from the tree readily, suspend 

 themselves by silken threads and then may be blown or carried 

 considerable distances. The full-grown caterpillars desert the 

 trees and wander considerably. This is particularly true of the 

 larger ones which almost invariably produce female moths. The 

 cocoons are spun very generally on the trunks or on the under- 

 side of the larger branches. 



Food plants. This leaf feeder exhibits a marked preference 

 in cities for the linden and horse-chestnut, while it feeds readily 

 on elms and maples. It has also been recorded on a number of 

 other trees. 



Natural enemies. This species has a number of natural ene- 

 mies. Its comparative rarity in the country shows that our 

 native birds must be very efficient natural checks upon this in- 

 sect. Mr E. H. Forbush states that forty-seven species of native 

 birds feed on hairy caterpillars, most of which would probably 

 take this leaf feeder. The robin, Baltimore oriole and cuckoo 

 are among the more valuable in this respect. 



Parasitic insects are also very efficient checks. This species is 

 subject to attack by some twenty-one primary parasites and these 

 in turn may become the prey of fourteen hyperparasites. 



Remedies. A simple and very satisfactory method of con- 

 trolling- this insect is the gathering and destroying of egg masses. 

 Several cities and villages in New York State have employed 

 children in this work by offering a small bounty and a system of 

 prizes. The result has been that a large number of egg masses 



