MOTHS AND BUTTERFLIES. 



453 



material with a silken thread, forming a rude case within which it transforms to a pupa. 

 There are two broods in a year, and the caterpillars feed on the leaves of apple, peach, 

 willow, grape, raspberry, strawberry, and smart-weed. 



Platycerura fwcilla expands about two inches. The fore wings are ashy white, 

 dusted with fine, dark scales, and the usual lines crossing the wings &re black. The 

 hind wings ai-e whitish, with a broad, obscure, dusky submarginal line. The mature 

 caterpillar is an inch and five-eighths in length, with the head and legs red. The body 

 is dull red, and much mottled with irregular, broken stripes of gray, whitish, and black. 

 The surface of the body is hairy, with several pencils of hairs one-fourth of an inch in 

 length. It feeds on white pine. 



The BombycidjE is a family of considerable extent, but the species are by no means 

 as numerous as in several of the other families of moths. The species vary so much 

 that some entomologists have arranged them in several families, but it is preferable 

 not to separate them. The majority of these moths have stout, hairy bodies, without 

 tufts of scales or hairs except in rare cases. Their heads are compai-atively small and 

 sunken, and the mouth-parts are obsolete in a majority of the species. The antennae 

 are broadly pectinated in tlie typical genera, at least in the males, and the ocelli are 

 present in some, but not in all the species. The wings are generally broad, and in 

 many species are gaily colored, while others are very plain. These moths have long 

 been noted for the strong attracting power which the virgin females exert on the males, 

 drawing them from long distances, and often in considerable numbers. Collectors of 

 these moths expose the unimpregnated females in suitable cages ; and, in favorable 

 weather, often secure a large number of males which are attracted to the cages contain- 

 ing the other sex. Browne states that he knew of a case where over sixteen hundred 

 of the males of a certain species were caught in one day by the attractive power of 

 seven or eight females. This method of collecting is called " assembling." Not only 

 males of the same species, but also of those which are nearly related are attracted, and, 

 when they are permitted to pair, produce hybrids as a result. 



The caterpillars are thick and hairy, or have more or less bristly spines over their 

 bodies ; and, with few exceptions, they spin cocoons in which they pass their trans- 

 formations. The silk of which some of their cocoons are made is manufactured into 

 various fabrics of great value and importance to mankind. In fact, the common silk- 

 worm, Bomhyx tnori, must be regarded as the most useful of all the insect tribes, since 

 it furnishes employment to a large 

 number of people in many countries, 

 who are employed in raising the cat- 

 erpillars and obtaining the cocoons, 

 which are afterwards unwound and 

 manufactured into such an endless 

 variety of fabrics. 



At the beginning of the bomby- 

 cids we meet a group of boring moths, 

 of which Xyleutes rohinim may be 

 taken as a type. The larvae bore in 

 the stems of various trees and plants, 

 the species figared attacking the red 

 oak and locust, while others attack the roots of the hop, etc. In these forms the wings 

 are rather membranous and strongly veined, recalling forms like the sialids among the 

 Neuroptera. 



Fig. B70. —Xyleutes robinice. 



