CANKER WORMS. 777 



General Summary. 



1906 1907 igoS 



Egg-masses laid during preceding year, 



number destroyed 29 118 73 



Egg-masses laid during same year, 



number destroyed 



Caterpillars, number destroyed 



Pupae, niunber destroyed 



Trees banded with burlap, number of. . . 



Funds expended by the state 



" " " " government . . 



CANKER WORMS. 



Spring Canker Worm, 



Paleacrita vernata Peck. 

 Fall Canker Worm, 



Alsophila pometaria Harris. 



Introduction. 

 The name canker worm is applied to two species of 

 insects similar in habits and appearance and closely 

 related, which are moths of the family Geometridae, 

 the larvae of which are known as "loopers" or "meas- 

 uring worms." Canker worms are of economic impor- 

 tance because they devour the foliage of various trees 

 and plants, often causing considerable injury. They 

 are general feeders and therefore attack a large number 

 of different kinds of trees, but seem to have a preference 

 for the foliage of apple, elm, chestnut, pear, oak, hick- 

 ory, box-elder and maple, in about the order named. 



Early Records. 

 The spring canker worm was first described by Pro- 

 fessor' W. D. Peck in 1795. The difference 

 Fig. 9. Canker between the sexes was known at this time, but 

 le^I^'Reducedf there was supposed to be only one species, evi- 

 dently vernata. The following is a quotation 

 from Peck's original account as published by Ridley.* 



f 



* Seventh Annual Report on the Noxious, Beneficial and Other Insects 

 of Missouri, 1874, p. 89. 



