14 
causing the sallows to throw out foliage early or late, and before 
the new leaves are fully developed. 
These galls are of a woody nature, and appear near the end 
of the boughs and twigs of some four or five species of salix, and 
are found during April or May. 
The Bulbous Gall. 
The swelling takes place very rapidly, and assumes a more 
or less bulbous shape, having a smooth surface, except where the 
outer skin of the twig has been unable to compete with the 
growth of the gall; the outline is then very uneven and ragged. 
One noticeable feature of this gall is that although the 
growth is of such an enormous size in Comparison with the twig 
on which it appears, the circumference of the twig is the same 
just beyond the gall swelling as it was before it reached the gall ; 
in fact, the deformity produced by this growth rises so abruptly 
from the surface of the twig and returns to it in a like manner, 
that it bears a striking resemblance to the kernel of a cracknut, 
with a little brown stick passed through it from base to apex. 
If one of these gall be cut open, there will be found a 
considerable number of oblong cavities wherein lie the larve. 
The cells are arranged in a very irregular manner, some near 
the centre, others close to the exterior walls of the gall, and in 
such close proximity that one grub often eats into the domain 
of its nearest neighbour. The larve are rather. pretty in 
colour. The body is more or less cylindrical in shape, divided 
into 13 or 14 segments, and, when fully grown, not quite an 
eighth of an inch long. The head is furnished with a pair of 
powerful black jaws. They do not appear to have any terminal 
outlet of the alimentary canal, therefore the cell is always quite 
clean. 
As many as fifteen to twenty larve inhabit an average size 
gall growth, each one having a separate cell. They undergo 
their transformations in the gall, the flies issuing forth during the 
month of June, leaving a round hole on the surface of the gall, 
through which it has made its escape. This gall is one of the 
polythalamous species. 
The common bramble furnishes us with the next example of 
gall growth. It is produced by the puncture of a little fly called 
Lasioptera Rubi. 
The larvee are much the same kind as those of the genus we 
have just considered, resembling them not only in colour but also 
in size and shape, and likewise in attacking plants in much the 
same way. 
