SHOT-BORER BEETLES. 75 
The following observations refer mainly to the much-to-be-regretted 
appearance of yet another kind of ‘‘Shot-borer”’ Beetle, namely, the 
Xyleborus saxeseni, as an infestation in wood of Plum trees. Up to the 
observation of its attacks in the early part of the past season, although 
the presence of this species in England was known of by entomologists, 
yet, so far as I am aware, there was no record of it having occurred 
here as a decided orchard pest, and naturally when the injuries were 
noticed they were attributed to the attacks of the Xyleborus dispar, 
which had caused much mischief at Toddington (Gloucestershire) and 
elsewhere a few years ago. 
Excepting to skilled examination, there is much similarity in the 
two attacks. I know of no difference in the appearance of the shot- 
hole-like perforations in the bark accompanying each. The beetles 
themselves require knowledge and a magnifier for differentiation, and 
the great and striking difference of the flat cells of the saweseni from the 
borings of the dispar are not noticeable without internal investigation 
of the attacked wood. Therefore, before entering on observations of 
the new pest, the saweseni, I have given the few following notes of the 
main characteristics, together with a figure of X. dispar for the sake 
of comparison (see p. 76). 
It will be only too well remembered by various leading orchard 
fruit-growers in the West of England that in 1889 a very small dark- 
brown beetle, which until that time had been considered one of our 
rarest species, appeared in such numbers as an infestation to Plum 
trees, as to cause serious mischief. From the bark of the attacked 
trees having the appearance of being perforated by shot-holes, the 
beetle is very commonly known as the ‘‘Shot-borer.” Scientifically, 
it is the Xyleborus dispar, from the disparity in size and shape between 
the male and female beetles. The female is about the eighth of an 
inch long, narrow, and cylindrical, with the fore body (thoraa) raised 
in the middle; the male is very minute, only about two-thirds of the 
length of the female, and broader in proportion, the thorax flatter 
than in the female (without the ‘‘hump’’). 
The injury is caused by the beetles boring their tunnels through 
the bark of the branches or young stems of Plum trees (or other trees, 
as the case may be, but in this country the young Plum trees are what 
suffer the most), and then sometimes running their galleries so as 
partially to ring them, or, after boring to the central pith, to clear out 
an inch or more of this (see figure, p. 76), or, again, to make upright 
tunnels in the hard wood, or sometimes run their tunnels so as quite 
to girdle the branches. From the nature of the injury, the flow of 
the sap is checked, and the tree is often killed with a rapidity which 
is unaccountable, until investigation shows what has been going on 
in the wood. 
