316 INSECTS INJURIOUS TO VEGETATION. 



minute warts thinly scattered over the surface of the body. 

 When fully grown, it measures two inches and a half, or more, 

 in length, and is nearly as thick as the end of the little finger. 

 These caterpillars bore the tree in various directions, but for 

 the most part obliquely upwards and downwards through the 

 solid wood, enlarging the holes as they increase in size, and 

 continuing them through the bark to the outside of the trunlfT" 

 Before transforming, they line these passages with a web of 

 silk, and, retiring to some distance from the orifice, they spin 

 around their bodies a closer web, or cocoon, within which they 

 assume the chrysalis form. The chrysalis measures one inch 

 and a half or two inches in length, is of an amber color, 

 changing to brown on the fore part of the body; and, on the 

 upper side of each abdominal ring, are two transverse rows of 

 tooth-like projections. By the help of these, the insect, when 

 ready for its last transformation, works its way to the mouth 

 of its burrow, where it remains while the chrysalis skin is rent, 

 upon which it comes forth on the trunk of the tree a winged 

 moth. In this its perfected state, it is of a gray color ; the fore 

 wings are thickly covered with dusky netted lines and irregular 

 spots, the hind wings are more uniformly dusky, and the 

 shoulder-covers are edged with black on the inside. It ex- 

 pands about three inches. The male, which is much smaller, 

 and has been mistaken for another species, is much darker 

 than the female, from which it differs also in having a large 

 ochre-yellow spot on the hind wings, contiguous to their pos- 

 terior margin. Professor Peck, who first made public the 

 history of this insect,* named it Cossiis Robinice, the Cossus 

 of the Locust-tree, scientifically called Robinia. It is supposed 

 by Professor Peck to remain three years in the caterpillar state. 

 The moth comes forth about the middle of July. The same 

 insect, or one not to be distinguished from it while a cater- 

 pillar, perforates the trunks of the red oak. Mr. Newman f has 

 recently given the name of Xi/leutes, the carpenter, to the genus 



* See Massachusetts Agricultural Repository and Journal," Vol. V., p. 67, with 

 a plate. 



t See "Entomological Magazine," Vol. V., p. 129. 



