THE FALL WEBWOKM. 



By R. E. Snodgrass, 

 Office of Fruit Insect Investigations, Bureau of Entomology. 



[With 2 plates.] 



Flu. 1. — Moths of the fall webworm (natural size). 



Could insects think and express their thoughts in terms that we 

 could understand we should probably hear complaints from them of 

 woods and fields disfigured by our barns and country houses and of 

 great areas devastated by our factories and towns. However, since 

 it happens that we are the ones that do the thinking, it is we that 

 express our thoughts in these same terms against the insects and 

 their works. People still ask why pests were made to annoy us and 

 to destroy our crops. But such questions imply a too egotistical 

 view of the situation. All of us, men and insects, are on the earth 

 for our own ends, and friction arises wherever interests overlap. 

 A caterpillar claims a certain tree as its natural food and habitat, 

 but we assert our property rights and proceed to drive the cater- 

 pillar out. Yet, though we never so intended, we have vastly im- 

 proved living conditions for many insect species by furnishing them 

 a far greater acreage of their favorite food plants than nature ever 

 provided. As a consequence they multiply in spite of our constant 

 war against them. 



In June silvery white bags of glistening silk appear amongst the 

 foliage of city, orchard, and woodland trees, each inclosing twigs 

 and leaves. As the season advances the bags increase in size, the 

 leaves within them die, and by fall they become objects of disgusting 

 ugliness, each perhaps spreading over several square feet of area. 

 These bags are the homes of the fall webworm, hairy caterpillars 

 which are the progeny of a small, white, night-flying moth (fig. 1) 



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