The Mosquito will be our first choice. As she leaps off from her light bark, the cast chrysalis skin of her early life beneath the waters, and sails away in the sunlight, her velvety wings fringed with silken hairs, and her neatly bodiced trim figure (though her nose is rather salient, considering that it is half as long as her entire body), present a beauty and grace of form and movement quite unsurpassed by her dipterous allies. She draws near and softly alights upon the hand of the charmed beholder, subdues her trumpeting notes, folds her wings noiselessly upon her back, daintily sets down one foot after the other, and with an eagerness chastened by the most refined delicacy for the feelings of her victim, and with the air of Velpeau redivivus, drives through crushed and bleeding capillaries, shrinking nerves and injured tissues, a many-bladed lancet of marvellous fineness, of wonderful complexity and fitness. While engorging herself with our blood, we will examine under the microscope the mosquito's mouth. The head (Fig. 61) is rounded, with the two eyes occupying a large part of the surface, and nearly meeting on the top of the head. Out of the forehead, so to speak, grow the long, delicate, hairy antennm (a), and just below arises the long beak which consists of the bristle-like maxillæ (mx, with their palpi, mp) and mandibles (m), and the single hair-like labrum, these five bristle-like organs being laid in the hollowed labium (l). Thus massed into a single awl-like beak, the mosquito, without any apparent effort, thrusts them all except the labium into the flesh. Her hind body may be seen tilling with the red blood, until it cries quits, and the insect withdraws its sting and flies sluggishly away. In a moment the wounded parts itch slightly, though a very robust person may not notice the irritation, or a more delicate individual if asleep; though if weakened by disease, or if stung in a highly vascular and sensitive part, such as the eyelid, the bite becomes really a serious matter. Multiply the mosquito a thousand fold, and one flees their attacks and avoids their haunts as he would a nest of hornets. Early in spring the larva (Fig. 62, A) of the mosquito may be found in pools and ditches. It remains at the bottom feeding upon decaying matter (thus acting as a scavenger, and in this state doing great benefit in clearing swamps of miasms), until it rises to the surface for air, which it inhales through a single respiratory tube (c) situated near the tail. When about to transform into the pupa state, it contracts and enlarges anteriorly near the middle, the larval skin is thrown off, and the insect appears in quite a different form (Fig. 62, a). The head and thorax are massed together, the rudiments of the mouth parts and of the wings and legs being folded upon the breast, while there are two breathing tubes (d) situated upon the back instead of the tail, which ends in two broad paddles (a); so that it comes to the surface, head foremost instead of tail first, a position according better with its increased age and experience in pond life. In a few days the pupa skin is cast; the insect, availing itself of its old habiliments as a raft upon which to float while its body is drying, grows lighter, and its wings expand for its marriage flight. The males are beautiful, both physically and morally, as they do not bite; their manners are more retiring than those of their stronger minded partners, as they rarely enter our dwellings, and live unnoticed in the woods. They may be easily distinguished from the females by their long maxillary palpi, and their thick, bushy, feathered antennæ. The female lays her elongated, oval eggs in a boat-shaped mass, which floats on the water. A mosquito lives three or four weeks in the water before changing to the adult or winged stage. How many days they live in the latter state we do not know.
62. Larva and Pupa of the Mosquito.
Our readers will understand, then, that all flies, like our mosquito for example, grow while in the larva and pupa state, and after they acquire wings do not grow, so that the small midges are not young mosquitoes, but the adult winged forms of an entirely different species and genus of fly; and the myriads of small flies, commonly supposed to be the young of larger flies, are adult forms belonging to different species of different genera, and perhaps of different families of the suborder of Diptera. The typical species of the genus Culex, to which the mosquito belongs, is Culex pipiens, described by Linnæus, and there are already over thirty North American species of this genus described in various works. Few insects live in the sea, but along the coast of New England a small, slender white larva (Fig. 63a, magnified, and head greatly enlarged; Fig. 64, pupa and fore foot of larva, showing the hooks), whose body is no thicker than a knitting needle, lives between tides, and has even been dredged at a depth of over a hundred feet, which transforms into a yellow mosquito-like fly (Fig. 65, with head of the female, magnified) which swarms in summer in immense numbers. I have called it provisionally Chironomus oceanicus, or Ocean gnat. The larvæ of other species have been found by Mr. S. I. Smith living at great depths in our Northern lakes. These kinds of gnats are usually seen early in spring hovering in swarms in mid air.
65. Ocean Gnat.
63. Larva of Ocean Gnat.
64. Pupa of Ocean Gnat.