328 



ANNUAL REPORT SMITHSONIAN INSTITUTION, 1924 



The advance winds of winter come surging over the hills in the west ; 

 drenching rains soak the chilling earth and make sodden masses of 

 summer's refuse that covers it. Now is the season when most of the 

 insects that will survive till spring are stowed away in their cocoons 

 or have found pi-otection in some retreat where they will await the 

 return of warmer weather. 



Yet, seeming to defy the laws of the insect world that impose 

 torpidity on other six-legged creatures and keep them in hiberna- 

 tion through the winter, the moths of the fall cankerworms now 

 break through their cocoons and emerge from the earth. Some law 

 of their own impels these creatures to undergo their transformation 

 and to deposit their eggs at this inclement season — eggs which are 

 not to hatch until the following spring. Any such striking example 



of exceptions to general rules shows 

 clearly that the nature of the reaction 

 by living things to external stimuli de- 

 pends on the inner nature of the creature 

 itself; the potency for individuality of 

 physical temperament in living matter 

 again asserts itself. 



The female moths of the fall canker- 

 worms (fig. 14) are very similar to those 

 of the spring species in size and general 

 appearance, though they are usually of 

 a more uniform light brown color. 

 They may be easily distinguished from 

 the spring canker moths, however, hj 

 the lack of spines on the abdominal seg- 

 ments, and by the short length of the 

 terminal hidden segments, which do not 

 form a protrusible tube for egg laying. 

 From the places where they leave the earth, the wingless moths 

 crawl through the grass and over the dead leaves that cover the 

 ground until they arrive at the trunk of a tree. In cases of unusual 

 abundance of cankerworm.s the moths may be observed in large 

 numbers as they issue from the earth. Dr. S. J. Hunter, describing 

 the emergence of spring cankerworms in Kansas in 1917, says: 

 "Around the base of the large elms, and for several feet away the 

 ground appeared to be moving, so abundant were the insects ; and as 

 these moved up the trees others kept emerging from the ground in 

 such numbers as to form a regular procession." Furthermore, he 

 adds: "The insects ascend, apparently alike, all standing objects. 

 Bands on maple trees caught as many as bands on adjoining trees. 

 The same can be said of telegraph poles or stone hitching posts." 



Fig. 14. — Female moth of the fall 

 cankenvorm (X 2%) 



