LIFE DisTonv. Mosquitoes in their early stages are all aquatic. The larvae need a cer tain amount of standing water for their develop ment. The eggs are laid by the adult insects, in the majority of eases upon the surface of stand ing water. They may he laid upon mid, at tached .side by side in raft-shaped masses, as in r ripiens and :ts in the genus Uranota.nia, or they may he laid singly on their sides. as in Anopheles, Sttgonlyia fuseiato, t'sorophora, and several species of Culex. They may also be laid upon moist earth in swampy places, as with soIic•ibvnls, or upon the leaves of pitcher plants. as with ornyirt fincilGii, hatching in these eases when water eventually reaches them. The eggs of some species. as those last minted and oligom}ia fascia la, will hear desiecation: but. the vitality of others. as those of .\noplieles, is destroyed When they are removed from the water for any length of time. The egg stage is temporary With re rhapa the majority of species, hut with others it is much longer, and may be the hibernating stage with certain forms. The larva is an active and voracious little creattn•e, and is commonly known as a 'wiggler' or 'wrig filer.' Its life as a rule is short, and with the great majority of the species it is a true air breather, coming to the surface of the water at frequent intervals and extruding its respiratory tube in order to suck air into its trachea. With at least one species (11'yeomyia Smithii), and perhaps with others. the anal locomotory flaps have an abundantly branched tracheal supply, and at least during, part of the larval life these flaps function as air-gills. rendering it possible for the larva to remain below- the surface of the water for a prolonged period of time. The food of mosquito larva is most variable. They swal low all sorts of minute organisms which float upon the surface or are held in suspension in the water. The larvae of Anopheles feed for the greater part of their life at the surface, and con sequently devour mainly the spores of alga; \\Ad& float there. Later in life in shallow water they descend to the bottom and feed upon heavier objects. The larva. of Culex feed below the sur face upon small organisms, animal and vegetable, and mineral as well, which are held in suspen sion. The larvw of Psorophora seem largely
carnivorous, and, on account of their large size, are able to overpower and to devour other mos quito larva and other aquatic insects. They are even cannibals, and will feed upon small indi viduals of their own kind. All mosquito larva are very active, wriggling quickly through the water by abrupt and rapid bendings of the body, aided in some cases by long lateral hairs. and especially by a well-developed group of flaps at the anal end of the body. Food is brought into the mouth by the active movement of long oral cilia. In many forms the jaws are undeveloped, but in some, as in Psoropliora, they are well formed and adapted for piercing and tearing.
The pupa is also active. hut does not feed, and possesses no mouth parts. As a rule it floats at the surface of the water, breathing through two iespiratory tubes which issue from the thorax—a curious change from the respiratory tube of the larva, incell is single and issues from the anal end of the abdomen. Although generally floating at the surface, the pupa when disturbed rapidly vanishes below the surface by energetic movements of the abdomen and of the anal flaps. and is thus enabled to a certain ex tent to avoid the attacks of fish and other ene mies. The pupal stage is usually of short dura tion. and the adult issues through the cracking of the skin of the thorax. With many mosquitoes there are several generations annually. With Cubs pipiens and Anopheles marulipennis, for example, there may be from eight to twelve such generations in a long summer. With other spe cies it seems reasonably certain that the life duration of the individual is much greater, and that in seine cases there may be but a single generation each year. lost mosquitoes hibernate as adults, stowing themselves away in protected places at the beginning of cold weather. Other species undoubtedly hibernate in the egg stage, and still others unquestionably hibernate as larvae, readily standing extremes of temperature. and even emerging in good condition with the warm weather of spring from blocks of ice in which they have been solidly frozen.