ith spines, especially towards the end of
the tail. They were a fifth of an inch in length. The last of June the
flies appeared, somewhat resembling gnats, and about a line long. The
worms continued to infest the tree for six weeks, the flies remaining
either upon or near it.

[Illustration: 71. Mouth Parts of Tabanus.]

We now come to that terror of our equine friends, the Horse fly, Gad, or
Breeze fly. In its larval state, some species live in water, and in damp
places under stones and pieces of wood, and others in the earth away
from water, where they feed on animal, and, probably, on decaying
matter. Mr. B. D. Walsh found an aquatic larva of this genus, which,
within a short time, devoured eleven water snails. Thus at this stage of
existence, this fly, often so destructive, even at times killing our
horses, is beneficial. During the hotter parts of summer, and when the
sun is shining brightly, thousands of these Horse flies appear on our
marshes and inland prairies. There are many different kinds, over one
hundred species of the genus Tabanus alone, living in North America. Our
most common species is the "Green head," or Tabanus lineola. When about
to bite, it settles quietly down upon the hand, face or foot, it matters
not which, and thrusts its formidable lancet-like jaws deep into the
flesh. Its bite is very painful, as we can testify from personal
experience. We were told during the last summer that a horse, which
stood fastened to a tree in a field near the marshes at Rowley, Mass.,
was bitten to death by these Green heads; and it is known that horses
and cattle are occasionally killed by their repeated harassing bites. In
cloudy weather they do not fly, and they perish on the cool frosty
nights of September. The Timb, or Tsetze fly, is a species of this group
of flies, and while it does not attack man, plagues to death, and is
said to poison by its bite, the cattle in certain districts of the
interior of Africa, thus almost barring out explorers. On comparing the
mouth-parts of the Horse fly (Fig. 71, mouth of T. lineola), we have all
the parts seen in the mosquito, but greatly modified. Like the mosquito,
the females alone bite, the male Horse fly being harmless, and
frequenting flowers, living upon their sweets. The labrum (_lb_),
mandibles (_m_) and maxillae (_mx_), are short, stiff and lancet-like,
and the maxillary palpi (_mp_; _a_, the five terminal joints of the
antennae) are large, stout, and two-join