252 INSECTS INJURIOUS TO VEGETATION. 



through the hole, in the stem or root, which the caterpillar had 

 previously made; and the shell of the chrysalis is left half 

 emerging from the orifice, after the moth has escaped from it. 



The ash-tree suffers very much from the attacks of borers of 

 this kind, which perforate the bark and sap-wood of the trunk 

 from the roots upwards, and are also found in all the branches 

 of any considerable size. The trees thus infested soon show 

 symptoms of disease, in the death of branches near the sum- 

 mit; and, when the insects become numerous, the trees no 

 longer increase in size and height, and premature decay and 

 death ensue. These borers assume the chrysalis form in the 

 month of June, and the chrysalids may be seen projecting half 

 way from the round holes in the bark of the tree in this and 

 the following month, during which time their final transforma- 

 tion is effected, and they burst open and escape from the shells 

 of the chrysalis in the winged or moth state. Under this form 

 this insect was described, in my paper in Professor Silliman's 

 "Journal of Science," by the name of Trochilium* denudatum; 

 as the habits of the larva are now ascertained, we may call it 

 the ash-tree Trochilium. Its general color is brown; the edges 

 of the collar and of the abdominal rings, the shins, the feet, 

 and the under side of the antennae are yellowish. The hind 

 wings are transparent; the fore wings are opake and brown, 

 variegated with rust-red ; they have a transparent space near 

 the tips, and expand about an inch and a half. 



During the month of August, the squash and other cucurbi- 

 taceous vines are frequently found to die suddenly down to the 

 root. The cause of this premature death is a little borer, which 

 begins its operations near the ground, perforates the stem, and 

 devours the interior. It afterwards enters the soil, forms a 

 cocoon of a gummy substance covered with particles of earth, 

 changes to a chrysalis, and comes forth the next summer a 

 winged insect. This is conspicuous for its orange-colored 

 body, spotted with black, and its hind legs fringed with long 



* The word Trochilium is derived from Trochilus, the scientific name of the 

 humming-bird genus ; and these insects are sometimes called humming-bird 

 moths. 



