584 



STATE BOARD OF AGRICULTURE. 



THE CANKER-WORMS. 



(Anisopteryx pometaria and Palcacrita vernata.) 



Very destructive insects are the canker-worms. Though easy to con- 

 quer if properly treated, the annual loss due to their depredations in our 

 State is very considerable. The past season has been no exception to 

 the general rule, for the insect has been present in destructive numbers 

 in various parts of the State. To judge from the letters inquiring for 

 remedies against this old-time pest, it would seem that many persons 

 have yet to learn the methods of fighting it. 



There are two species of canker-worms more or less common where- 

 ever apples are raised; the fall canker-worm and the spring canker- 

 worm. The fall worm (Figs. 14, 15) is perhaps the more common; it is 

 a single-brooded insect, which lays its eggs either late in the autumn or 

 early in spring. The egg hatches out a small loop-worm that grows to 

 the length of nearly an inch. It varies greatly in color, but is usually 

 grey or almost black, striped with yellowish or greenish. Being a 

 measuring-w r orm, it has less than the ordinary number of legs, six true 

 legs near the head and four false legs near the posterior extremity, with 

 an extra rudimentary pair on the fifth abdominal segment. When full- 

 grown it descends to the ground and usually buries itself, sometimes 

 several inches beneath the surface. Here it forms a cell by turning 

 round and round, and changes to the pupal stage. Late in the fall, from 

 the last of October to the time when the ground becomes frozen, the 

 adults emerge and lay their eggs on the branches of the trees. Many 

 of the moths do not emerge in the fall, but remain in the ground till 

 spring. When adult, the two sexes differ greatly in appearance. The 

 male is a pretty moth with ash-grey front wings marked by three trans- 

 verse darker lines, and hind wings of silvery grey (Fig. 14, a). The 

 female, on the other hand, is not provided with wings, but has to crawl 

 wherever she goes. She is somewhat more robust than the male and ash- 

 grey in color, marked with black (Fig. 14, b). 





Fig. 14. Fall Canker-worm (Anisopteryx, pome- 

 taria); a, male: b, female; c, <l, e, structural 

 details. 



Fig. 15. Fall Canker-worm (Anisopteryx pome- 

 taria); a. o, egg, enlarged: e, patch of eggs; 

 r. ri. body segments of; /. larva; g, pupa of 

 female. 



The life-history of the spring canker-worm conforms in most important 

 particulars to that of the one described, except that the adults do not 



