CANKERWORMS — SNODGRASS 



333 



the insect organism. A study of insect "psychology" is likely to 

 open many new lines of attack in our efforts to control the ravages 

 of injurious species. 



When the female fall cankerworm moth is ready to deposit her 

 eggs, she selects a site most anywhere on the limbs or twigs of the 

 tree she has ascended. The eggs are stuck to the surface of the bark 

 (fig. 16, A), not tucked away dn cracks or crevices as are those of the 

 spring cankerworm. Wlien placed on a large limb they are spread out 

 in a flat mass, but on smaller branches the mass is curved to fit the con- 

 tour, and on the twigs it may almost completely encircle the support 



B 



Pio., 17. — Eggs of the fall canker- 

 worm. A, egg mass on a twig : 

 B, group of eggs, side view ; C, 

 group of eggs seen from above 



Pig. 18. — Female fall cankerworra 

 moths exhausted after egg laying. 

 A, B, moths still sitting on twig ; 

 C, moth lying helpless on her back 

 after falling from the twig 



like a cylindrical jacket (fig. 16, B). Each egg looks like a minia- 

 ture earthenware jar (fig. 17, B, C), gi-ayish in color, flat on top, 

 rounded at the bottom. The eggs all stand close together, fastened to 

 the bark by a gluey substance which the female discharges from 

 glands connected with the opening of her egg duct. The eggs are 

 often so evenly placed that their tops form regular rows in three 

 directions across the surface of the mass. Usually there are between 

 200 and 300 eggs in each mass, but there may be as many as 400. 



After disposing of her eggs, the female in most cases is shrunken 

 and exhausted. Of tAvo moths that deposited the last of their eggs 

 in captivity on November 9 and 10, respectively, one sat beside them 



