ELM-BARK BEETLE. 45 
A few other trees are slightly attacked. Is there any fear of it 
spreading ?”’ 
The little beetles which cause this serious injury are of the shape 
figured at p. 43, only about a quarter of an inch or less in length, and 
less than half that measure in breadth, of a black colour, with the 
wing-cases, which are square-cornered, reddish or sometimes black or 
pitchy, the shanks and feet reddish or lighter brown than the beetle, 
and the horns (antenne) also reddish or lighter brown, short, slightly 
elbowed, with the lowest joint long, and the terminal joints forming 
a club. 
The grubs are whitish, curved, fleshy, much wrinkled across, and 
legless, and have the three first segments swelled in shape, which 
serves to distinguish them from others of the many parasitic larve or 
other co-tenants of the infested bark. 
The attack begins towards the end of May or beginning of June, 
and though it is considered to be mostly to trees which from some cause 
are not in full health, yet it may be to the stems of young as well as 
old, and healthy as well as sickly trees. 
The females work their way along the bottom of cracks in the bark, 
widening them, it is stated, as they go along before beginning their 
tunnels for egg-laying. These tunnels may be from three to five 
inches long, and take about three weeks to form. The eggs are laid 
along each side, and may be above a hundred in number. As the 
grubs hatch from the eggs, they each start gnawing their tunnels at 
right angles from the parent gallery,—the size of the tunnel being 
enlarged to accommodate the increasing size of the larva; so that 
where there are many eggs laid closely side by side, there very soon 
ceases to be room for all the grubs, and the tunnels of. the strongest 
and most rapid in working take all the space, and the weaker grubs 
perish. Many of the grubs are full-fed towards the end of July, and 
turn to the pupal or chrysalis state at the end of their burrows, and 
the beetles from these pierce through the bark, and come out from the 
tree in August, the little shot-hole-like perforations showing where 
they have escaped. 
The greater number of the grubs, however, appear to pass the 
winter either just within the wood or in the thick bark, and to come 
out as beetles in May, ready to begin summer attack. It is considered 
that they prefer a tree which has already been attacked rather than 
one which is sound and vigorous, and in which consequently the full 
flow of sap might be prejudicial to the young grubs; and, so far as I 
have been able to watch the attack myself, I believe that the great 
proportion of it will be found to be to trees not in their full vigour. 
The above remarks give a general description of this very injurious 
timber infestation, of which it may be remarked in passing that it has 
