296 INSECTS OF MASSACHUSETTS. 



destructive to the tree as the painted Clytus, is a very much 

 larger borer, and is occasionally productive of great injury, espe- 

 cially to full-grown and old trees, for which it appears to have a 

 preference. It is a true caterpillar, belonging to the tribe of 

 moths under consideration, is reddish above, and white beneath, 

 with the head and top of the first ring brown and shelly, and there 

 are a (ew short hairs arising from minute warts thinly scattered 

 over the surface of the body. When fully growr, 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 down- 

 wards through the solid wood, enlarging the holes as they in- 

 crease in size, and continuing them through the bark to the out- 

 side of the trunk. 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 forepart 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 expands about three inches. 

 The male, which is much smaller, and has been mistaken for an- 

 other 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 posterior margin. Professor Peck, who first 

 made public the history of this insect*, named it Cossus Uobinice, 

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

 supposed by Professor Peck to remain three years in the cater- 



* Sec ''Massachusetts Agricultural Repository and Journal," Vol. V., p. G7, 

 with a plate 



