INSECTS THAT PREY UPON LOCUST-TREES. 
345 
should be preserved and bred with care. It is to 
them that we are hereafter to look for such fleeces 
as can bear exportation to England and France, at 
a good profit. These foreign countries can procure 
the coarser qualities of wool elsewhere, and at a 
cheaper rate than the United States can at present 
produce them; but in the very fine qualities, we 
are persuaded no country can compete with us, if 
we continue growing them with the steady perse¬ 
verance which usually characterizes our most in¬ 
telligent and spirited sheep-masters. 
INSECTS THAT PREY UPON LOCUST-TREES. 
Locust-Tree Borer ( Cossus robiniae). —Fig. 81 . 
The Robinia pseudacacia, in Europe, is very free 
from the attack of insects; but in those parts of the 
United States where this tree is cultivated, it is 
preyed upon by three distinct species of borers, or 
wood-eaters, the unchecked operations of which 
threaten an almost entire destruction of this valu¬ 
able tree. Dr. T. W. Harris, in his “ Report on the 
Insects of Massachusetts injurious to Vegetation,” 
observes that, “ One of these borers is a little red¬ 
dish caterpillar, whose operations are confined to the 
small branches and to very young trees, in the pith 
of which it lives ; and by its irritation it causes the 
twig to swell around the part attacked. These 
swellings, being spongy, and also perforated by the 
caterpillar, are weaker than the rest of the stem, 
which therefore easily breaks off at these places. 
My attempts to complete the history of this insect 
have not been successful hitherto; and I can only 
conjecture that it belongs to the iEgerians, or pos¬ 
sibly to the tribe of Bombyces.” In the same work, 
he describes a second kind of borer, called Clytus 
pictus or the painted clytus. “ In the month of 
September,” he says, “ these beetles gather on the 
locust-trees, where they may be seen glittering in 
the sun-beams, with their gorgeous livery of black 
velvet and gold, coursing up and down the trunks 
in pursuit of their mates, or to drive away their 
rivals, and stopping every now and then to salute 
those they meet, with a rapid bowing of the shoul¬ 
ders, accompanied by a creaking sound, indicative 
of recognition or defiance. Having paired, the 
female, attended by her partner, creeps over the 
bark, searching the crevices with her antennae, and 
dropping therein her snow-white eggs, in clusters 
of seven or eight together, and at intervals of five 
or six minutes, till her whole stock is safely stored. 
The eggs are soon hatched, and the grubs imme 
diateiy burrow into the bark, devouring the soft, 
inner substance, that suffices for their nourishment 
till the approach of winter, during which they re¬ 
main at rest in a torpid state. In the spring, they 
bore through the sap-wood, more or less deeply 
into the trunk, the general course of their winding 
and irregular passages being in an upward direc¬ 
tion from the place of their entrance. For a time, 
they cast their chips out of their holes as fast as 
they are made, but, after awhile, the passage be¬ 
comes clogged, and the burrow more or less filled 
with the coarse and fibrous fragments of wood, to 
get rid of which, the grubs are often obliged to open 
new holes through the bark. The seat of their 
operations is known by the oozing of the sap and 
dropping of the saw-dust from the holes. The 
bark around the part attacked begins to swell, and 
in a few years the trunk and limbs will become dis¬ 
figured and weakened by large porous tumors, 
caused by the efforts of the trees to repair the inju¬ 
ries they have suffered.” According to the obser¬ 
vations of a writer in the “ Massachusetts Agricul¬ 
tural Repository and Journal,” vol. vi., the larvae of 
this insect attain their full size by the 20th of July, 
soon after which they pass into the pupa state, and 
are transformed into beetles early in September. 
The third class of borers which attack this tree, is 
the Xyleutes robiniae or locust-tree carpenter moth, 
of Harris; or the Cossus robiniae, described and 
figured by Professor Peck, in the fifth volume of the 
“ Massachusetts Agricultural Repository and Jour¬ 
nal.” According to Michaux, the ravages of these 
insects were first observed about sixty years ago ; 
but their habits were not generally known before 
the year 1803, when they first attracted the atten¬ 
tion of Professor Peck, of Harvard University. He 
observed several locust-trees that had been blown 
down by a storm, which were much bored by the 
larvae of these insects, with their heart-wood dead. 
In splitting some billets of these trees, he found 
that they contained several of the caterpillars or 
borers, of different magnitudes, which enabled him 
to watch them through the various stages of their 
growth. “ The furrows in the bark of the locust,” 
says he, “ are large and deep, extending, in some 
places, even to the liber or inner bark. It must be 
in the deepest of these furrows, that the egg to 
produce the caterpillar is deposited. The inner 
bark is thick and succulent, affording to the young 
larvae a tender and proper food. The sap-wood is 
harder; this, too, is perforated to the perfect or 
heart-wood, on which it is afterwards to feed. 
This it bores in various directions, obliquely, up¬ 
ward and downward, making them larger as it in¬ 
creases in bulk. Some of these perforations are 
large enough to admit the little finger. The grubs 
of the wood-eating beetles always provide a path 
for the escape of the perfect insect out of the wood, 
before they go into the nympha or chrysalis state. 
In the same manner does the caterpillar of the 
locust form an opening quite through the bark, 
before it forms its cocoon. An inspection of the 
scene of its labors clearly discovers how everything 
is done.” Professor Peck supposed that the larva 
