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ANNUAL REPORT SMITHSONIAN INSTITUTION, 1924 



on the twig for a day and a half, the other for two whole days. Most 

 of the time each maintained the curious attitude shown at A and B 

 of Figure 18, the body being propped up almost vertical on the front 

 and hind pairs of legs, while the two middle legs were slowly waved 

 in the air. Finally the moths became so weak that the legs failed 

 to maintain the grasp on the twig, and each in turn dropped to the 

 surface of the table below, landing legs upward, and remained help- 

 lessly in this position. But life was not yet extinct. The female that 

 deposited her eggs on the ninth lay for three full days slowly moving 

 one leg (fig, 18, C) ; the other showed similar but decreasing signs 

 of life, until finally there was but a feeble trembling of one foot. Both 

 died on the 14th, five and four days, respectively, after egg laying. 



On the other hand, active and plump-looking females are some- 

 times taken out of doors, which, when killed and dissected, are found 

 to be completely devoid of eggs. These eggless females almost 

 always have a large bubble of gas in the thorax, contained in a sack- 

 like pouch of the cesophagus. Specimens with eggs were never found 

 to contain this air bubble. All of the females, however, undoubtedly 

 soon perish ; and the males must encounter a similar fate. 



The lives of these creatures seem to us to be but periods of miserable 

 existence, activated by an incomprehensible devotion to a physical 

 duty. Yet, there is no reason to believe that they suffer; they are 

 simply differently constituted in some way from the majority of 

 insects. Their lives are as normal as are those of the warmth-loving 

 moths that flock to our lights on hot summer evenings, or of the seem- 

 ingly care-free butterflies that frequent our gardens on sunny after- 

 noons, where they meet their affinities or refresh themselves from the 

 nectar of the flowers. 



The eggs of the fall cankerworm remain on the trees all winter to 

 hatch next spring about the first of May, or about the time the new 

 leaves are unfolding. When nature gives the signal, the caterpillar 

 within the egg gnaws an irregular hole in the top of its cell large 

 enough to permit its head to emerge (fig. 19). Then a long, slim 

 body suddenly shoots out, pulls itself free from its prison, and the 

 young cankerworm loops away in search of its first meal. 



Fia. 19. — Young fall cankerworms emerging from the eggs (greatly enlarged) 



