CANKER WORMS. 795 



longitudinally with fine pale lines. They have no pro-legs on 

 the eighth segment. They spin down on fine silken threads when 

 disturbed, and become full grown about June Ist, going into the 

 ground, making a simple earthen cell lined with a few threads 

 of silk. The male pupa is tipped with a simple spine. 



The adult male has a wing spread of about an inch and is 

 of a brownish gray color. Wings are thin and semitransparent, 

 with the markings rather indistinct. Female, brown or gray, 

 with a black or dark brown stripe along the back and a two- 

 jointed exsertile ovipositor. 



The fall canker worm, Alsophild pometaria Harris, is far more 

 common in New England than the spring species, though both 

 occur. The adults appear in November and December, and the 

 females lay dark gray eggs on the trees in compact clusters of 

 about one hundred, arranged in rows, and each egg fastened by 

 one end to the bark. The caterpillars hatch from the eggs e^rly 

 in May, and vary in color from light green to dark gray or 

 brown, marked lengthwise with fine white lines. A pair of pro- 

 legs is borne on the eighth segment. Like the spring species, they 

 spin down on silken threads, and are about three-fourths of an 

 inch long when full grown, about June ist, when they go into 

 the ground to pupate. The pupa is stouter than in the spring 

 canker worm and the spine is curved and forked. It is enclosed 

 in a silken cocoon interwoven with soil particles, making a strong 

 cell. 



The adult male is lightly larger than vernata, brownish gray 

 in color, with a slight purplish tinge, wings are firmer, less trans- 

 parent and darker gray in color. The fore wings are crossed by 

 two whitish bands, the distal one being offset inward on the costal 

 margin, forming a white costal spot. Female without wings, 

 markings, or visible ovipositor, and uniform ash-gray in color. 



Both kinds of canker worms devour the leaves of trees in the 

 same way, and attack a large number of different kinds of trees. 

 The fall species seems to be especially fond of apple orchards. 



Spraying the trees with Paris green was first advised in the 

 early eighties, while bands covered with tar and printers' ink have 

 remained in use. 



At the present time the best treatment for orchards is to spray 

 with lead arsenate (three pounds in fifty gallons of water or 



S6 



