ENTOMOLOGY IN OUTLINE LEPIDOPTER A. 77 



sometimes entangling the whole tree with its webs. They live in com- 

 munities, feed in droves, and are capable of doing great damage, unless 

 checked. 



The family Bombyeidse includes the true silkworms. The true silk- 

 worm (Bombyx mori) appears to be an invention of man in the insect 

 world. Its origin is unknown, none of its species existing in the wild 

 state, and it has been so long under cultivation that it can not live 

 unless cared for by man. 



The family Platypterygidse has a few representatives among us, but 

 they are of no economic importance. 



The family Geometridse includes those caterpillars commonly known 

 as loopers, inch-worms, measuring-worms, etc. They are all vegetable 

 feeders and very destructive. In it we find the currant span-worm, the 

 spring and fall cankerworms, and many others too well known to our 

 fruit-growers. Over eight hundred species are known to exist in the 

 United States 

 and Canada. 

 The caterpillars 

 lack all save one 

 pair, or in some 



cases two pairs, FIG. 71. Fall cankerwonn (Alsophila pometaria). a, male moth; 



. .1 i b, female moth; c, joints of antennae of female, enlarged; 



<l. segment of body of emale, enlarged : e, larva. 



found in other 



caterpillars, and in moving are compelled to make the peculiar motions 

 which give them their popular names. They first extend the body its 

 full length, then bring the posterior end close up to the forelegs, loop- 

 ing the body in the middle, then stretch out the fore part of the body 

 again, and continue these motions until they reach their desired desti- 

 nation. The moths have slender bodies, small heads, and very broad, 

 thin wings. In many species the females are wingless, as in the 

 cankerworms. 



The family Epiplemidse is a small one, closely related to the Geom- 

 eters, but of little importance to us. 



The family Nolidse is another small one of rather small moths, which 

 are of little interest except to the systematic entomologist. 



The family Laeosomidse is a small one, and consists of moths pecul- 

 iar to the western hemisphere. It is thus described by Holland: 

 ''While the perfect insects show structural resemblances to the Pla- 

 typterygidse, the caterpillars, which have the habit of constructing for 

 themselves portable cases out of leaves, which they drag about with 



