96 INSECTS INJURIOUS TO FOREST AND SHADE TREES. 
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 becomes 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 the dropping of the sawdust from 
the holes. The bark around the part attacked begins to swell, and in a few years the 
trunk and limbs will become disfigured and weakened by large porous tumors, caused 
by the efforts of the trees to repair the injuries they have suffered. According to the 
observations of General H. A. 8. Dearborn, who has given an excellent account* of 
this insect, the grubs attain their full size by the 20th of July, soon become pupz, and 
are changed to beetles and leave the trees early in September. Thus the existence of 
this species is limited to one year. 
As is well known, this species also attacks the walnut and hickory, and occasionally 
the honey-locust, but those individuals living in these trees, unlike the locust brood, 
evolve the beetle in June, according to Walsh, who has claimed that the males of the 
hickory-brood differ from those of the locust-brood in having “much longer and stouter 
legs and much longer and stouter antenne, and in having [their bodies] tapered be- 
hind to a blunt point”; on the other hand the females are not distinguishable, nor the 
larve. On this aceount Mr. Walsh regarded the locust and hickory broods as represent- 
ing two distinct species, a view not now entertained. He gives, however, some inter- 
esting facts in the Practical Entomologist, vol. i, p. 29, regarding the appearance of this 
insect in the Western States, as follows: 
The history of this species is very curious, and as it has only recently been eluci- 
dated by myself, and some additional details can now be added, may be briefly summed 
up as follows: About a hundred years ago this insect was well known to Forster to 
inhabit the locust in the State of New York. Twenty years ago, although the best 
Illinois botanists agree that the locust grows wild in the Southern part of Illinois, it 
was still unknown in that State. Shortly afterwards it commenced attacking the 
locusts in the neighborhood of Chicago, and thence spread gradually in a south-south- 
west and west direction through the State, sweeping the locusts before it wherever 
it came. In 1860, it had pretty well destroyed all these trees in Central Illinois. 
Rock Island lies on the Mississippi River 180 miles south of west from Chicago. In 
1862 it had reached a point 20 miles east of Rock Island. In 1863 it burst forth sud- 
denly in great swarms from all the locusts in Rock Island, and the two following 
years about completed their destruction. It has now (1865) crossed the river into 
Iowa, and no doubt will continue its travels westward as long as it finds any locust 
trees to prey on. 
Lest it should be supposed that, agreeably to the belief of all the older writers, the 
species that inhabit the hickory is identical with that which inhabits the locust, it is 
proper to add here, that I myself split the hickory insect out of a stick of hickory 
wood, as much as eight years ago in Rock Island; that abundance of hickory grows 
in the woods within half a mile of that city, and yet that our locust trees were never 
attacked by borers until 1863, when they were suddenly attacked in the manner men- 
tioned above. Professor Sheldon, of Davenport, Iowa, has also repeatedly, for many 
years before 1863, split the hickory insect out of hickory wood in Davenport, although, 
*Dr. Horn, who has observed this borer in the hickory, states (Proc. Ent. Soc. Phil., 
i, 30) that its excavations are immediately subcortical. ‘Unlike the Clytus erythro- 
cephalus, which also bores in the hickory, its course is not in a line, but it bores in 
every direction, making extensive excavations. Its borings are coarse and sawdust- 
like, and are packed with considerable firmness. When about to become a pupa the 
larva bores for a slight depth into the wood, and for a distance of about three inches. 
The aperture is closed with some very coarse splinter-like borings, and after having 
turned its head in the direction of its previous subcortical dwelling, it undergoes its 
transformation, and requires about two and sometimes three weeks for becoming a 
perfect insect.” 
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