Vine Galls
Of these, by far the most to be dreaded are the Galls produced on stems and leaves by Phylloxera vastatrix (see Grape or Vine Louse). The only other Galls on Vines in Europe worth mention are pale, hairy growths (Erineum Vitis) caused by Mites (Phytoptus), in patches on the lower surface of the leaves, and two produced by Gall-midges. Of these, one is a swelling of the twigs, and is the work of an undetermined species of Midge (Cecidomyia); it occurs in the South of France, and in the South of Russia. The other produces swellings, not unlike those of Phylloxera, on the leaves. They are about 1/10in. in diameter, conical on the upper surface, and more rounded below. Several grow in each leaf. This Gall has been found in Austria.
The North American Vine Galls are far more varied in size and form than the European, and several of them attain considerable size. All that will be referred to here are the work of Gall-midges (Cecidomyia). The "Filbert Gall" is developed form a bud, and forms a mass 1 1/2in. to 2 1/2in. in diameter, made up of from ten to forty woolly, greenish, juicy Galls, each tenanted by one orange-yellow larva. The "Tomato Gall" consists of an irregular mass of juicy, yellowish-green or red swellings, each occupied by four or five larval chambers, with one orange-yellow larva of Lasioptera Vitis in each. The whole mass may reach from 1in. to 4in. across.
The "Apple Gall" is attached to the stem, and is like a hazel-nut in form. It is nearly 1in. in diameter. There are eight or nine furrows down the surface, which correspond to chambers in the interior, in an upper and a lower series. Each is occupied by a bright yellow larva of a Cecidomyia. The gall is juicy, and the surface is covered with short, downy hairs. The "Trumpet Gall" rises from the upper (rarely the lower) surface of the leaf. As a rule, many stand on each leaf, two or three often being united at the base. These Galls are about 1/3in. long by 1/20in. broad in the widest part; they taper a little towards the base, and the other end is sharp. Their colour varies from bright red to green.
Remedy. None of the above Galls have yet been recorded from England. Should any of them be introduced with European or American Vines, they should be removed from the plants while still young and soft: no further remedy is needed.