Page:Popular Science Monthly Volume 5.djvu/15

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5
THE GRAPE PHYLLOXERA.

Soon after the first vine-leaves that put out in the spring have fully expanded, a few scattering galls may be found, mostly on the lower leaves, nearest the ground. These vernal galls are usually large (of the size of an ordinary pea), and the normal green is often blushed with rose where exposed to the light of the sun. On opening one of them (Fig. 3;d) we shall find the mother-louse diligently at work surrounding

Fig. 1.
PSM V05 D015 Leaf covered with galls.jpg
Leaf covered with Galls.

herself with pale-yellow eggs of an elongate oval form, scarcely .01 inch long, and not quite half as thick (Fig. 3, c). She is about .04 inch long, generally spherical in shape, of a dull orange-color, and looks not unlike an immature seed of the common purslane. At times, by the elongation of the abdomen, the shape assumes, more or less perfectly, the pyriform. Her members are all dusky, and so

Fig. 2.
PSM V05 D015 Elongated galls.jpg
a and b, elongated galls; c and d, upper and under side of abortive galls.

short compared to her swollen body, that she appears very clumsy, and undoubtedly would be outside of her gall, which she never has occasion to quit, and which serves her alike as dwelling-house and coffin. The eggs begin to hatch, when six or eight days old, into active little oval, hexapod beings, which differ from their mother in their brighter yellow color and more perfect legs and antennae, the tarsi being furnished with long, pliant hairs, terminating in a more or less distinct globule. These hairs were called digituli by Dr. Shimer, and