faces, crawl under one's clothes, where they even
remain and bite in the night. The children in the house were sickly and
worn by their unceasing torments; and the shaggy Newfoundland dogs whose
thick coats would seem to be proof against their bites ran from their
shelter beneath the bench and dashed into the river, their only retreat.
In cloudy weather, unlike the mosquito, the black fly disappears, only
flying when the sun shines. The bite of the black fly is often severe,
the creature leaving a large clot of blood to mark the scene of its
surgical triumphs. Prof. E. T. Cox, State Geologist of Indiana, has sent
us specimens of a much larger fly, which Baron Osten Sacken refers to
this genus, which is called on the prairies, where it is said to bite
horses to death, the Buffalo Gnat. Westwood states that an allied fly
(Rhagio Columbaschensis) is one of the greatest scourges of man and
beast in Hungary, where it has been known to kill cattle.

[Illustration: 68. Black fly.]

[Illustration: 69. Black Fly Larva.]

The Simulium molestum (Fig. 68, enlarged), as the black fly is called,
lives during the larva state in the water. The larva of a Labrador
species (Fig. 69, enlarged) which we found, is about a quarter of an
inch long, and of the appearance here indicated. The pupa is also
aquatic, having long respiratory filaments attached to each side of the
front of the thorax. According to Westwood, "the posterior part of its
body is enclosed in a semioval membranous cocoon, which is at first
formed by the larva, the anterior part of which is eaten away before
changing to a pupa, so as to be open in front. The imago is produced
beneath the surface of the water, its fine silky covering serving to
repel the action of the water."

[Illustration: 70. Mycetobia.]

Multitudes of a long, slender, white worm may often be found living in
the dirt, and sour sap running from wounds in the elm tree. Two summers
ago we discovered some of these larvae, and on rearing them found that
they were a species of Mycetobia (Fig. 70; _a_, larva; _b_, pupa). The
larva is remarkable for having the abdominal segments divided into two
portions, the hinder much smaller than the anterior division. Its whole
length is a little over a third of an inch. The pupae were found sticking
out in considerable numbers from the tree, being anchored by the little
spines at the tail. The head is square, ending in two horns, and the
body is straight and covered w