Page:The Olive Its Culture in Theory and Practice.djvu/126

104 forming for each a niche which is enclosed by a partition made of bits of wood agglutinated with saliva, and in twenty or thirty days, from thirty to thirty-two eggs are deposited.

Sometimes two females will enter at the same aperture and after the first part of the gallery is completed will bore in opposite directions, often taking the form of a T (Fig. 1. e.) or a Y (Fig. 1. d.)

The working of the insect is manifested by a small tumor or windgall resembling soap foam which issues from the holes made by them on entering. These excrescences are composed of excrement and fibres of the wood mixed with salivary fluid. The eggs hatch in fifteen days from the time they are deposited. The larvae nourish themselves from the fibre of the wood boring secondary tunnels, the first perpendicular, with parallel ones between, resembling much the reeds of an organ (Fig. 1. e.)

The greatest length of a gallery or tunnel never exceeds three quarters of an inch and is less than one-twelfth of an inch in diameter. The number of the lateral tunnels are not usually more than twenty on the same line or thirty on two lines. When the female has finished depositing her eggs she crawls to the external orifice of the gallery and dies.

At the end of thirty or forty days the larva having reached the maximum stage of development, bores into the bottom of its own gallery, an oval niche (Fig. 1. e.) in which it remains immovable and without food for eight or ten days. From this stage it passes into that of the chrysalis casting its abdominal appendage. At the end of another ten days (Fig. 10) the chrysalis becomes a perfect insect which proceeds to gnaw the new wood of the tree, and the bark about its cell, emerging according to the season, in April or May. It flutters for a short time about the tree and then settles down, and bores a hole at the fork of a bearing or blossoming branch, which being deprived of its necessary nutriment soon languishes and dies. In a few days the mating takes place and about the first of June the boring of the tunnels for the depositing