862 [Assembly 
are the excrement of a larva which lives in the walls of the gall, 
mining cylindrical channels in it. This larva is about the tenth 
of an inch long, shining watery whitish, with a pale yellow cloud 
iri the middle of its body, from visceral matter in the intestines, 
and a flattened polished pale tawny head with the jaws appearing 
like two brown dots on its anterior edge. It has no feet, and to 
crawl forward it elongates itself and with its jaws grasps the 
spongy side of its burrow, and then contracting, it draws its body 
up towards its head. By this singular mode of progression it 
moves along with rapidity in its burrow, but when placed upon 
paper it strives in wain to lay hold of the smooth surface with its 
jaws, and is incapable of advancing. It is quite probable that 
this worm is the larva of the Elegant weevil above spokep of. 
It would be supposed that the lice which occupy these galls, 
being wholly shut in as they are by a thick wall upon every side, 
would be secure from the assaults of the numerous and inveterate 
enemies of the aphides which have been noticed in the preceding 
pages. But in one instance, four worms, which from their appear¬ 
ance and motions I supposed to be the larvae of a Syrphusfly, 
were met with in one of these galls. They were the tenth of an 
inch long, of an elongated oval form, more pointed anteriorly, 
and of a pale rose-red color, with a broad yellow stripe in the mid¬ 
dle from inclosed visceral matter. 
Though I have not been able to find winged individuals of 
the insect which forms the galls upon the hickory twigs, it is so 
like the Pemphigus bursarius of Europe in its habits, a species 
which forms similar galls upon the leafstalks of the poplar, that 
I entertain no doubt our insect is co-generic with that species. 
We have still another species which is closely related to these in 
its habits. It is the grape leaf louse (Pemphigus Vitifolicc ) of my 
manuscripts, and forms small globular galls about the size of a 
pea, upon the margin of the leaves of the grape vine. They are 
of a red or pale yellow color, and their surface is somewhat 
uneven and woolly. They are met with the fore part of June, hav¬ 
ing only the wingless females inclosed within them at that time. 
These closely resemble the same sex in the species under con¬ 
sideration . 
