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Pear Tree Insects

Pear Tree InsectsThe caterpillars of the Wood Leopard Moth feed in the live wood of many kinds of trees. They are to be found in Pear, Apple, Plum, and Walnut; also in Ash, Beech, Birch, Elm, Holly, Lime, Oak, and others, besides Horse Chestnut (Aesculus hippocastanum), from which the moth takes its specific name, though not appropriately, as it rarely attacks this tree.

The eggs are laid during July, or later in the summer, in crevices of the bark, and on the branches as well as the trunk of the trees ; these eggs are oval and salmon-coloured, and as many as three hundred have been seen laid by one moth. The caterpillars, which soon hatch, feed at first in the bark, but not long afterwards they make their way into the live wood, where they bore galleries rather wider than themselves, and as much as a foot in length, When full grown they are about an inch and a half long, whitish, or yellow, or ochry, with a black horny plate on the segment behind the head, and the tail segment also is partially black and horny. The other segments have each four raised black spots on each side, and the head is black, or has two black spots.

They feed (or feed at intervals) through the winter until May or June (statements are made that they live for two years), and, when full-fed, they spin a web, or form a case of wood-dust, in which they change to an ochreous brown, long, cylindrical chrysalis. This web is usually woven just inside the bark, near the entrance of the boring, so that when the time for development is come the chrysalis forces itself through the opening, and, by means of the fine prickles with which it is furnished along the back, it is held firmly in the web whilst the moth frees itself, and leaves the empty case projecting from the tree.

The moth is large and handsome, the female from about 2.25 to 2.75 inches in spread of the wings, the male much smaller. The wings are somewhat transparent, and are white with blackish or blue-black spots, the spots being darkest on the fore wings, which also have yellow veins. The body between the wings is white spotted with black, and the abdomen, grey, or grey banded with black.

It is stated that the female moths appear somewhat later than the male, and may be found until the end of August. Specimens of this attack, chiefly in caterpillar stage, are not unfrequently sent me, but it is very rarely mentioned as being prevalent.

The caterpillars may be controlled (like those of the Goat Moth) by drawing them out of their burrows with hooked wires, or by running a strong wire into the hole, and thus crushing the caterpillar within to death. If the wire, when withdrawn, is found to have wet whitish matter on it, such as would result from having crushed the larva, or again, if gnawed wood should have been passed out of the burrow up to the time of the operation and no more appear afterwards, it may be supposed the creature is killed; otherwise the operation should be repeated.

Syringing is also of service in getting rid of these caterpillars. For this purpose a gutta-percha tube with a sharp­pointed nozzle may be fitted to the syringe, and thus, by placing the point of the nozzle well into the hole, it may be filled with strong soft-soap, or any mixture that may be preferred, such as will make the hole too unpleasant or poisonous for the grub to remain in, even if it is not killed by the application. This moth is preyed on by bats.