330 
LEPIDOPTERA. 
Fig. 158. 
and the edo^es of the abdominal seornents are armed with 
o o 
transverse rows of short teeth. By means of these little 
teeth, the chrysalis, just before it is about to be transformed 
to a winged insect, works its way out of 
the cocoon, and partly through the hole, in 
the stem or root, Avhich the caterpillar had 
previously made; and the shell of the chrys¬ 
alis (Fig. 158) is left half emerging from the 
orifice, after the moth has escaped from it. 
Tlie ash-tree suffers verv much from the attacks of borers 
V 
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 summit; and,*Avhen the insects become 
numerous, the trees no lono-er increase in size and height, 
and premature decay and death ensue. These borers as¬ 
sume the chrvsalis form in the month of June, and the 
chiysalids may be seen projecting half-way from the round 
holes in the bark of the tree in this and the folloAvino: 
month, durincT Avhich time their final transformation is ef- 
fected, and they burst open and escape from the shells 
of the chrvsalis in the Avino-ed or moth state. Under this 
t, O 
form this insect Avas described, in my paper in Professor 
Silliman’s “Journal of Science,” by the name of Trochi- 
lium* denudatum ; as the habits of the laiwa are noAv 
ascertained, Ave may call it the ash-tree Trocliilmm. Its 
o-eneral color is broAvn; the edc-es of the collar and of 
the abdominal rings, the shins, the feet, and the under 
side of the antennas are yelloAvish. The hind AAlnois are 
transparent; the fore Avings are opaque and broAAm, A^arie- 
gated AAdth rust-red ; they have a transparent space near the 
tips, and expand about an inch and a half. 
* The word TrochiUum is derived from Trodiilus, the scientific name of the 
humming-bird genus; aud these insects are sometimes called humming-bird 
moths. 
