length. The female insect bores a hole with its strong ovipositor in the bark of the fir, in which a single egg is deposited. After seven weeks the larva has attained its full size, when it is usually buried six inches deep in the wood; here it remains a long time in a pupa state, and as the eggs are usually deposited in cut trees in preference to growing one, the pupæ are often found in squared and cut timber. The yellow body of the female insect is terminated by the sheath of the ovipositor, which the uninitiated are prone to regard as its sting; and hence the insect always inspires dread. As the female will lay some hundreds of eggs during the season, it is by no means a rare insect, but must be sought amongst pine-trees. Larch posts and palings are subject to its attacks. Strange stories have been told of this insect, but they bear so little of the impress of veracity that it were better not to repeat them.

There is one feature of the wings in many of these insects which will interest the microscopist. This consists in the row of hooks with which the upper edges of the hind wings are furnished. Not alone one feature but many await the investigator of their minute structure; the saws of the "sawflies," the ovipositors of the ichneumons, the stings of wasps and bees, the eyes of all, it would be long ere all the wonders are exhausted which the microscope would reveal in the minute anatomy of these four-winged flies.

CHAPTER XII.

TWO-WINGED FLIES.

called by There are

TWO-WINGED Flies, or Diptera, as they are entomologists, are exceedingly numerous. said to be not less than ten thousand species in Europe distributed through six hundred and eighty genera, but in this country their study is exceedingly limited, yet the number must be very large. Their habits are very variable. The greater number act as scavengers in the water and on the land, and thus become sanitary agents. They are the earliest to appear in spring, and the latest to depart in autumn. Active at all times, by night and by day, in rain or in sunshine, most of them prefer the latter. This book has no pretension to being a guide to species, or the task here would be a formidable one, and therefore we shall rest content with brief allusions to some

of the most important groups. Of these the Gnat family need not detain us; for although some of them fly in woods, they are more associated with the ponds and ditches in which the larvæ are reared. The twowinged gall-flies are termed Cecidomyida, and these on the contrary are addicted to vegetation of all

kinds, whether in gardens, woods, or cultivated fields, where they inflict considerable injury. They are mostly very small, and are sometimes called "Midges," indeed many of them are quite microscopic; such as the wheat-midges, so destructive to wheat. These insects are usually studied in association with the galls, distortions, and deformations of the plants which they inhabit. They are in themselves so tiny and delicate, and so difficult to preserve, that it is fortunate for the entomologist that he obtains so much assistance in the prosecution of his studies from the malformation of the foster-plants. The larvæ live in preference on living plants, nevertheless some species have occurred in rotten wood, and some dwell beneath the bark of trees, or in the cones of firs. Most of the larvæ confine themselves to one species of plant, whilst some inhabit the galls of other species as parasites. Those found under the bark of trees live for the most part in company with other larvæ. It is probable that the little orange-larvæ which are found so commonly living on the orange Uredinous fungi belong to this group. These little creatures, which resemble small maggots, will be seen crawling over the under surface of the leaves of coltsfoot, when it is infested with its habitual orange rust. All the larvæ have fourteen joints, which is an apparent exception from all other larvæ, which as a general rule have thirteen.

Every part of a plant, from the root to the flower and fruit, is subject to their attacks, but each species usually attacks the same part of the plant, and deforms it in the same way. These deformations are

very numerous; at one extreme of the series is the true gall, a growth of constant and definite form, attached to the plant by a very small portion of its surface, and at the other extreme a simple deformation, as for instance the folding of a leaf, the swelling of the veins of a leaf, or the arrest of the growth of a bud or a stalk. Several attempts have been made to classify the insects according to the nature and shape of these malformations.

The injury which these minute insects inflict is out of all proportion to their size. One little fly not a line in length, and with a larva scarce half the size of a caraway-seed, attacks the twigs of osier willows,1 and perforate them to such an extent as to render them wholly unfit for basket-making. The little flies when on the wing swarm about the low boggy places where osiers are cultivated. It is very customary for country people to call all the little two-winged flies "midges," which congregate in flocks, but these are much more commonly Ephemera.

Another of the "midges" attacks the larger willows, and this is a little larger than the preceding species.2 The bark flakes off, or is bored so as to be easily removed, and then the surface of the wood is found to be burrowed into a number of elongated cells, in each of which a minute orange maggot will be found. This little pest is scarcely so large as a caraway-seed, which it resembles in shape, being entirely destitute of legs. From this condition it passes into the pupa stage. When ready to emerge as a perfect

Cecidomyia viminalis.

2 Cecidomyia saliciperda.

insect, these pupæ thrust themselves halfway out of the circular hole in which they have been resident, and even after the insects have escaped, the empty cases may be seen protruding from the holes in the bark and wood. The fly is something like a small gnat, with a dark grey body, terminated, in the case of the female, by a long borer, which enables the insect to introduce its eggs in the crevices of bark.

A similar midge has been known to attack poplars, but those already named will be sufficient illustrations of a numerous group of destructive little insects.

Daddy Long-legs and Old Father Long-legs are the trivial names given to the large gnats, which in autumn are swarming in our pasture-lands, fields, and pleasure-grounds, and in some gardens bordering on low lands they are frequently abundant. In the United States it is the spider-like creature called Harvestman which is called Daddy Long-legs. Familiar as every child is with Daddy Long-legs, its transformations and history are but imperfectly known, and even cultivators seldom suspect that the surface grubs, or Leather Jackets, as the dirty-looking larvæ are called which do so much mischief in marketgardens, are the offspring of our old and familiar acquaintance. It is impossible to glance along palings, rails, and even on tree-trunks near parks and grassy places, in September or early in October, without observing these gnats, especially in the morning, with legs extended and wings half-spread, under the shade of thorns and trees, five-sixths of these insects being females. Even later in chill and frosty mornings they are often abundant, hanging by their fore-feet, cheer

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