THE GNATS. 75 



slightly thickened at the tip. This proboscis in the females contains all the parts that are ever found 

 in a Dipterous insect, the bristles representing the mandibles and maxillae being present and free, 

 together with the fifth bristle or epipharynx. The mandibles are wanting in the males. The maxillae 

 have a pair of palpi, of four joints, and comparatively short in the females, of live joints, very long and 

 often more or less hairy in the males. The antennse are long and slender, composed of fourteen 

 joints, and furnished with whorls of hairs, which become very long and dense in the males, giving 

 them a beautifully feathered appearance. The head is small, and bears a pair of lunate eyes, but no 

 ocelli ; the thorax is stout ; and the abdomen slender and delicate ; the legs are very long and thin, 

 and the veins of the wings are densely clothed with scale-like hairs. 



These insects, which are only too well known for their blood- sucking propensities and the 

 intense irritation often produced by their bites, are inhabitants of the water in their preparatory 

 state, and it is accordingly in the neighbourhood of water and in wet seasons that they especially 

 abound. The eggs, which are of an elongated form, are deposited by the female, with the assistance 

 of her hind legs, upon the surface of the water in a small boat-like mass, the eggs being arranged and 

 closely packed together side by side with their pointed end uppermost (Fig. 4, p. 76). From the shape 

 of the eggs, which are a little broader at one end than at the other, the whole mass of eggs 

 necessarily acquires a slight curve like that of a shallow spoon, and the larger ends being down- 

 wards, the concavity of the spoon is above, and the little collection of eggs floats securely like a boat 

 upon the surface of the water, until the larvae are hatched. This soon occurs in favourable weather, 

 and the larvae descend into the water, where they may be constantly seen during the spring and 

 summer, swimming about with great agility by a violent jerking motion of the body, or suspending 

 themselves from time to time head downwards at the surface of the water, for the purpose of breathing 

 through a curious air- tube, with which they are provided near the tail (Fig. 5, p. 76). This tube 

 springs from the eighth segment of the abdomen, and its apex is surrounded by a circlet of bristles, 

 which, by closing, prevents the entrance of water when the larva is submerged, but opens like a little 

 star when the orifice is brought to the surface of the water, and thus gives free ingress to the air, and 

 at the same time assists in suspending the larva from the surface. The terminal segment of the 

 abdomen, which is beyond the origin of this tube, is fringed with bristles and terminated by five 

 slender, conical plates. The larva has a distinct rounded head, which is furnished with a pair of 

 antennae, and between these with a pair of jaws fringed with very curious bristles (Figs. 6, 7, 8, p. 76). 

 The latter organs create a sort of whirlpool in the water, which serves to convey to the mouth of the 

 insect the floating particles of more or less nutritive matter that come within its reach. These 

 curious larvae change their skin three times, and then become converted into pupae (Fig. 9, p. 76),, 

 in which the parts of the perfect insects are rudely indicated ; they continue to swim about by the- 

 agency of the abdomen, which is terminated by a pair of thin leaf-like organs. In this condition 

 the insects of course no longer take any nourishment, but, like the larvae, they still suspend them- 

 selves at the surface of the water in order to respire air; their position when, thus engaged is, however, 

 the reverse of that of the larvae, the breathing-organs being now two short tubes, like truncated horns, 

 which spring from the sides of the thoracic region. When the perfect Gnat is ready to emerge the 

 pupa conies to the surface of the water, and remains there quite still, until the skin of its back, 

 which is exposed to the air, dries and splits longitudinally. The perfect insect then slowly emerges, 

 disengaging one part of its body after the other from the pupa-skin, which, during this operation, 

 acts the part of a boat or raft, for the support of its previous inmate, until the wings of the latter 

 have acquired sufficient firmness to enable it to rise into the air. In rough weather these frail boats 

 often prove insufficient, and many Gnats get drowned before their wings are dried (Fig. 10, p. 76). 



After their emergence, these delicate creatures, or at least the males, pass their time in a series 

 of aerial dances, in which great swarms of them may often be seen engaged ; in fact, so numerous are 

 the insects in certain seasons and localities, that their swarms have sometimes the appearance of great 

 smoke clouds surrounding and ascending from some lofty building, such as the spire of a church. As 

 each female lays about 300 eggs, and the development of the insects occupies only four weeks, 

 it is easy to understand how this extraordinary number of individuals may be produced by the 

 successive generations in the course of the spring and summer, if the external conditions are 

 favourable. The females of the last generation of the season, after fecundation, retire to sheltered 



