784 
ANNUAL REPORT OF NEW YORK 
OAK. TRUNK. 
brownish-yellow and the scutel dull yellow. The inner sides of its thighs 
are slightly dusky. 
AFFECTING THE TRUNK. 
293* Locust Cossus, Cossus Robinicc , Peck. (Lcpidoptera. Ucpialidco.) 
Boring large holes in the solid wood of the different kinds of oaks and 
also in the locust, admitting the air and moisture to the interior of their 
trunks and causing their decay; a large cylindrical worm of a bright rose 
red color, with several purple pimples symmetrically arranged, each yield¬ 
ing a hair, its under side greenish white, with sixteen’legs, and its head 
shining black ; when fully grown three inches in length and as thick as 
one s finger, and then appearing of a dull flesh-color instead of red and its 
head tawny yellow; passing its pupa state in a cocoon in the tree, and 
coming abroad in June and July, a large thick-bodied motli of a gray 
color with a black stripe on each side of its thorax, and its fore wings with 
black clouds and a net-work of black lines, when extended measuring three 
inches in width ; the male smaller and more colored with black, with the 
hind half of its hind wings bright orange yellow, its width 2.00 to 2.30. 
Of all the wood-boring insects in our land this is by far the most per¬ 
nicious, wounding the trees the most cruelly. The stateliest oaks in our 
forests are ruined, probably in every instance where one of these borers 
obtains a lodgment in their trunks. It perforates a hole the size of a half¬ 
inch auger, or large enough to admit the little finger, and requiring thre 
or four years for the bark to close together over it. This hole running 
inward to the heart of the tree, and admitting the water thereto from every 
shower that passes, causes a decay in the wood to commence, and the tree 
never regains its previous soundness. 
This is also a most prolific insect. The abdomen of the female is so 
filled and distended with eggs that it becomes unwicldly and inert, falling 
rom side to side as its position is shifted. A specimen which I once 
obtained, extruded upwards of three hundred eggs within a few hours aftc 
its capture, its abdomen becoming diminished hereby to nearly half its 
previous bulk; and in the analogous European species more than a thou¬ 
sand eggs have been found on dissection. It hence appears that a single 
one of these insects is capable of ruining a whole forest of oak trees. This 
calamity, however, is prevented, probably by most of the eggs being 
destroyed, either by birds or by other insects, for these borers are by no 
means so common in our trees as the fecundity of their parents would lead 
us to expect. 
An account of this insect was first given in the year 1818, in an article 
written by the late Prof. Peck, but published anonymously, in the Massa¬ 
chusetts Agricultural Repository, vol. v. pp. G7-73. Having bred tho 
moth from larvae which he found in the locust (Robinia Pseud-acacia) and 
ascertained its intimate relationship to the European goat-moth, named 
Bombyx Cossus by Linnaeus and Cossus ligniperda by Fabricius, Prof. 
P eck bestowed the name Cossus Robinice upon our insect. Dr. Harris 
