Pine Weevils
Hylobius Abietis is a beetle very hurtful to the Scotch Fir, and to various other Conifers, as it feeds, in the perfect state, on the bark of the young shoots. It is seldom very destructive in gardens, or in pleasure-grounds, but does most harm amongst young trees growing in the neighbourhood of recently-felled plantations, where brushwood, &c., has been lying about for some time. The beetles are 1/2 in. to 3/4 in. long, dull black, with scattered tufts of yellow hairs. The thorax is narrowed in front, and the head is small, and bears a decurved proboscis, on which are the antennae, abruptly elbowed at the tip of the long first or basal joint. The wing-cases are rough, with lines of pits and tubercles, and there are numerous small pits on the head. The beetles appear from May to July. They gnaw the buds and the bark of the twigs, interfering, in this way, with the development of the trees. The eggs are laid in crevices on stumps of Firs, on logs, and on cut branches; and the white, legless larvae, on hatching, burrow into the wood, and feed on it, making galleries that increase in size with their own growth. At the end of the burrow, a cocoon is formed, by the full-fed larva, of the fragments gnawed by it in making the gallery. Here, in spring, it becomes a pupa, in which state it passes about four weeks.
Pissodes notatus and P. Pini belong to a genus closely allied to Hylobius, and are not less hurtful. They are, however, easily known from that genus by having the antennae in the middle of the narrowed beak, while Hylobius has them situated quite near its tip. The thorax also is broader compared with the wing-cases. Both species of Pissodes are rather smaller than Hylobius Abietis. In general appearance and colour, they agree not a little with that beetle. They are of a pitchy-brown colour, but this is modified by a coating of yellowish-white scales or hairs, more conspicuous in certain parts. Their general appearance is shown Both are about 1/3 in. long. The larvae of P. notatus live under the bark of living trees of good size; and those of P. Pini in old stumps, &c., making winding galleries, in which, when full-fed, they spin oval cocoons of fragments of wood and silk. The beetles emerge from July to September. As beetles, they destroy the young branches of Conifers by boring small holes in them, and sucking the sap Resin is apt to flow out from the openings, and the branches die, and fall off.
Prevention. This is best insured by the removal and burning of the branches, &c., cut off in wood-cutting operations. The supply of food for the larvae is thus stopped. The perfect insects may be caught by using, as traps, flat pieces of bark, laid on the ground under weights, and frequently examining them; from these the beetles can be picked off. Or cut branches may be placed in suitable localities, and the beetles attracted to them may be shaken off and killed. A few logs should be left for a time, to induce the females to lay their eggs thereon; but they should be burned while the larvae are still in them. Young Conifers should not be planted on the site of an old plantation, where numerous stumps serve as breeding-places for the beetles. Hand-picking is of use where the trees to be protected are few and small.