Cantharis vittata. Potato Fly.
Description. — The Potato Fly is found principally in the middle and southern States ; it makes its appearance in July and August, and feeds upon the potato plant. Some seasons the fly exists in great numbers. It resembles the Spanish Fly, though somewhat smaller, being about five or six lines in length. Its head is of a light-red color, with dark spots upon the top ; the antennae are black ; the elytra or wing covers are also black, with a central yellow longitudinal line, and yellow margins; the thorax is black, with three yellow lines ; and the abdomen and legs are covered with an ash-colored down. During the season of their appearance, they may be found on the plant in the morning and evening, but during the heat of the day, they descend into the soil. They may be collected by shaking them from the plant into hot water, after which they should be carefully dried in the sun.
History. — The Potato Fly, though not so much employed as the Spanish Fly, is fully equal, if not superior to it as a vesicant ; indeed, its effects are found to take place more promptly than with the foreign insect, which may, probably, be owing to its greater freshness.
There are several other species of blistering fly in the United States, which are, probably, not at all inferior to cantharides ; as the Cantharis Cinerea, or ash-colored cantharis which inhabits the northern and middle States ; the C. Atrata, or black cantharis, common to the northern and middle States, and likewise found in Barbary ; the C. Marginata of the middle and eastern States, and which feeds on the various species of clematis, and also on the cimicifuga; and likewise the G. Alvida, C. Nuttalli, etc.
Properties and Uses. — The vesicating property of all these insects, is very likely owing to the presence of the same proximate principle, and therefore they may be applied to the same purposes, and administered in the same doses and preparations as the Spanish Cantharis.