Page images
PDF
EPUB

pierce through the toughest hide. It is stated that they will not touch a horse whose back has been well washed with a strong decoction of walnut leaves. The eyes of these flies are very beautiful, and vary in their colors and markings in the different species.

The golden-eyed forest-flies are also distinguished for the brilliancy of their spotted eyes, and for their clouded or banded wings. They are much smaller than the horse-flies, but resemble them in their habits. Some of them are entirely black (Chrysops ferrugatus, Fabricius), others are striped with black and yellow (Chrysops vittatus, Wiedemann). They frequent woods and thickets, in July and August.

The bee-flies, or Bombylians (BOMBYLIADE), have a very slender proboscis, sometimes exceeding the length of their body. They are met with in sunny paths in the woods, in April and May. They fly with great swiftness, stop suddenly every little while, and, balancing themselves with their long, horizontally spread wings, seem to hang suspended in the air. They often hover, in this way, over the early flowers, sucking out the honey thereof, like humming-birds, with their long bills. Our largest bee-fly is the Bombylius æqualis, so named by Fabricius, because the wings are divided lengthwise, in their color, into two equal parts, the outer part being brownish black, and the inner half colorless and transparent. The body of this insect is short, rounded, and covered with yellowish hairs, like a humble-bee. It measures three eighths of an inch in length, and the wings expand rather more than seven eighths of an inch.

There are some fies that prey on other insects, catching them on the wing or on plants, and sucking out their juices. Some of them have thick and hairy bodies and legs, and bear a striking resemblance to our biggest humble-bees. Such are the Laphria thoracica, of Fabricius, which is black, with yellow hairs on the top of the thorax, and measures eight or nine tenths of an inch in length; another species, which may be called Laphria flavibarbis, differing from the former in having the face and sides of the head covered with a yellow beard, and in being an inch or more long; and the Laphria tergissa, of Say, which is somewhat like the last, but has yellow hairs on the three middle segments of the bind body, and on the shanks of the anterior and middle pairs of legs, and measures about an inch in length. These insects belong to a family called Asilidæ, from Asilus, the principal genus. In the larva state, those of the Asilians, whose habits are known, live in the ground upon the roots of plants, and sometimes do considerable mischief, as proved to be the case with some that were sent to me last May, by the Rev. Thomas Hill, of Waltham, who found them devouring the roots of the tart rhubarb. They were yellowish white maggots, about three quarters of an inch long, not perfectly cylindrical, but a little depressed, and tapering at each end. The head was small, brown, and partially drawn within the first ring, and was provided with two little horny brown hooks. There was a pair of breathingpores on the first ring, and another pair on the last but one. These maggots were transformed in the earth to naked pupæ, having the limbs free. The pupa was brown, and had a pair of short horns on the forehead, three spines on each side of the head, a forked tail, and a transverse row of little teeth across the middle of each ring of the hind body. When about to undergo their last transformation, the pupæ work their way to the surface of the ground by the help of the little teeth on their rings. I have repeatedly seen the empty pupa-shells sticking half way out of the ground around rhubarb plants. In the fore part of July, there issued from these pupæ some long-bodied flies, which proved to be of the species called Asilus sericeus, by Mr. Say. The body of this insect is slen. der and tapering, and measures from eight tenths of an inch to one inch and one tenth in length. It is of a brownish yellow color, covered with a short silky down, varying in different lights from golden yellow to brown, and with a broad brown stripe on the top of the thorax. The wings are smoky brown, with broad brownish yellow veins, and expand one inch and a quarter, or more. We have several other kinds of Asilus, some larger, and others smaller than the foregoing, of whose history nothing is known, except their predaceous habits in the winged state, which have been often observed. There are also several slender kinds of Laphria; but these are easily distinguished from every species of Asilus by their antennæ, which are not, as in the latter, tipped with a slender point, but are blunt at the end.

Besides the foregoing, there are many other rapacious flies, some of which are of great size. The largest one found here is the orange-banded Midas (Midas filatus*), specimens of which are sometimes found measuring an inch and a quarter in length, with wings expanding two inches and a quarter. It is black, with an orange-colored band on the second ring of the hind body; and the wings are smoky brown, with a metallic lustre. It receives its scientific name, filatus, signifying threadlike, from its antennæ, which are long and slender, but they end with an oblong oval knob. Its generical name was also given to it on account of its long antennæ; Midas, in Mythology, being the name of a person fabled to have had the long ears of an ass. The orange-banded Midas may often be seen flying in the woods in July and August, or resting and basking in the sun upon fallen trees. Its transformations have never been described. Its larva and pupa almost exactly resemble those of the rapacious Asilians. The larva is a cylindrical, whitish maggot, tapering before, and almost rounded behind; it has only two breathing-holes, which are placed in the last ring but one; and it grows to the length of two inches. It lives and undergoes its transformations in decayed logs and stumps. The pupa measures about an inch and a quarter in length; it is of a brown color, and nearly cylindrical shape; its tail is forked; there are eight thorns on the fore part of its body; and each ring of the abdomen is edged with numerous sharp teeth, like a saw, all these teeth pointing backwards except those on the back of the first ring, which are directed forwards. The pupa pushes itself half way out of the stump when the fly is about to come forth, and the latter makes its escape by splitting open the back of the pupa-skin.

In the month of June, there may sometimes be seen, resting on the grass or on rotten stumps, in open woods, a large, light

Incorrectly named Mydas filata, by Fabricius.

brown or drab-colored fly, somewhat like a horse-fly in form, but easily distinguished therefrom by two little thorns on the hinder part of the thorax; and by the wings, which do not spread so much when the insect is at rest. It is heavy and sluggish in its motions, and does not attempt to fly away when approached. This insect was called Cænomyia pallida, the pale Cænomyia, by Mr. Say, in the Appendix to Keating's “ Narrative," and in the second volume of the "American Entomology," where it is figured. The generical name, signifying a common fly, is rather unfortunate, for this is a rare insect. The only specimens known to Mr. Say were found by him in a small forest of scattered trees, on the Pecktannos river, in Wisconsin Territory. A few have been taken in Massachusetts, one of them on Blue Hill, in Milton; and Mr. Gosse found three specimens, in as many years, in Canada. In its transformations this insect is more nearly related to the gad-flies and the Asilians than to the soldier-flies, near which it has generally been placed; though it approaches the latter in its structure, and in its sluggish habits. The larvæ or maggots, though not yet discovered, undoubtedly live in the ground, or in decayed vegetable substances, like those of the horse-flies and other predatory insects; for Mr. Gosse found one of his specimens, on the grass, in the act of emerging from the pupaskin. He has also figured* the pupa, which is of a chestnutbrown color, and has transverse rows of spines on the abdominal rings.

Most of the soldier-flies (STRATIOMYADÆ) are armed with two thorns or sharp spines on the hinder part of the thorax. They form the first family of the flies that undergo their transformations within the hardened skin of the larva, which is not thrown off till they break through it to come out in the winged state. Their proboscis contains, at most, only four bristles, is not fitted for piercing, but ends with large fleshy lips, by means whereof these flies suck the sweet juices of flowers. Most of them are found in wet places, where their larvæ live; some of the latter being provided with a tube, in the hinder extremity,

• “Canadian Naturalist," p. 199.

which they thrust out of the water in order to breathe. The skin of these larvæ is merely shortened a little, without wholly losing its former shape, when the inclosed insects change to pupæ; thereby showing that this family is truly intermediate between the preceding flies, which cast off their larva-skins, and those which retain them, and take an oblong oval shape, when they become pupæ. Some of the soldier-flies (Stratyomys) have a broad oval body, ornamented with yellow triangles or crescents on each side of the back, and their antennæ are somewhat like those of Midas and of the gad-flies; others ( Sargus) are slender, often of a brilliant brassy green color, with a bristle on the tip of their antennæ. The maggots of the latter live in rich mould.

The Syrphians (SYRPHIDÆ) have a fleshy, large-lipped proboscis, elbowed near the base, and enclosing only four slender bristles. They live on the honey of Aowers. The last joint of their short antennæ bears a bristle, which is sometimes feathered. Their heads are large and hemispherical. Many of these flies are often mistaken for bees or wasps, and some of them lay their eggs in the nests of the insects they so closely resemble. Others drop their eggs among plant-lice, which their young afterwards destroy in great numbers. The larvæ of a few are aquatic, and are provided with very long, tubular tails, through which they breathe, and have been called rattailed maggots. Some of the largest and most beautiful of these flies live, in the maggot state, in rotten wood. One of these rat-tailed flies is often seen on windows, in the autumn. It flies with a buzzing noise. Its eyes are very large, and of a bright copper-color; its body is brassy green; and there are five gray stripes on the thorax. It measures about four tenths of an inch in length. It is the Eristalis sincerus of my " Catalogue.” The Milesia excentrica, named in the same work, strikingly resembles a hornet; its hind body being banded with black and yellow in the same way. Its head and thorax are black, the former margined around the eyes, and the latter spotted, with yellowish wbite. The legs are ochre-yellow, except the shanks and feet of the first pair, which are black. Its body measures nearly three quarters of an inch in length.

« PreviousContinue »