94 
PLUM. 
and much wider in proportion, and the back is flatter. The wings 
which I examined in the female were well-developed, and thickly 
sprinkled with very short, bulbous-rooted bristles. 
Another peculiarity has been considered to be the extreme rarity of 
males compared to the number of females, and amongst from about 
fifty to sixty of these Shot-borers which I took out of their borings in 
Plum-stems in September, I found only one male. Subsequent search, 
however, made me think that in winter the difference in proportion of 
numbers would be found to be not nearly so great, for amongst some 
specimens I examined early in December I found a larger proportion 
of males; and about a month later, amongst specimens I took (on or 
about January 10th) from a piece of Plum-stem two inches and a 
quarter across, about seventeen males to six females. 
The borings at this winter time of year only contained a sprinkling 
of beetles, instead of, as in September, being so crowded up that there 
was scarcely room to insert another beetle into the row that filled each 
boring. 
The reason of the singularly rapid and complete destruction of the 
stem of the young trees attacked by these beetles is plainly shown on 
laying open their tunnels. In the specimens from Toddington which 
I examined (figured life-size at p. 92), I found that the injury began by 
a small hole like a shot-hole being bored in the side of the attacked 
stem, from which a tunnel ran to the pith, and a branch about the 
eighth of an inch across ran horizontally about half or two-thirds 
round the stem. Sometimes this tunnel was about midway between 
the outside and the centre, but in one instance quite at the outside of 
the wood. From these horizontal borings other borings were taken 
straight up and down the stem; these might be certainly as many as 
four (perhaps more in one stem), and were from half an inch to 
upwards of an inch and a half long, and of these tunnels (in the pieces 
of stem I examined), one ran along the pith, which was completely 
cleared away. The great injury caused by these galleries fully 
accounted for the death of the stem. 
At the time of examination, that is, on or about September 12th, 
the tunnels were filled with beetles; where the width only was enough 
for one, the beetles were arranged in a row one after another in pro¬ 
cession, as it were ; where the tunnel was a little wider (as where the 
pith had been cleared away), they were less regularly arranged, but 
crowded in, so that there scarcely seemed to be room for another. In 
one length of wood of about two inches I found, as near as might be, 
thirty beetles. The w r ork of destruction was still evidently going on, 
for in some instances I found that, instead of being as usual black and 
discoloured, the sides of the tunnel or the extremity were white and 
moist, showing the beetles were still feeding. The instinct of tunnelling Q 
