. A manual for the study of insects. Insects. DIPTERA. 439 molts changes into a club-shaped pupa, the head and thorax being greatly enlarged (514, b). With this transformation a remarkable change takes place in the respi- ratory system. There are now two breath- ing-tubes, and these are borne by the thorax. One of these tubes is represented greatly enlarged by Figure 5I5,<^. At the tail-end of the body there is a pair of leaf- ^ Fig. 515.—Uy end of like appendae^es, with which the insect breathing-tube of larva; ^ ^ ° 0, breathing-tube of swims; for the pupc'e of mosquitoes, and p"p^'
. A manual for the study of insects. Insects. DIPTERA. 439 molts changes into a club-shaped pupa, the head and thorax being greatly enlarged (514, b). With this transformation a remarkable change takes place in the respi- ratory system. There are now two breath- ing-tubes, and these are borne by the thorax. One of these tubes is represented greatly enlarged by Figure 5I5,<^. At the tail-end of the body there is a pair of leaf- ^ Fig. 515.—Uy end of like appendae^es, with which the insect breathing-tube of larva; ^ ^ ° 0, breathing-tube of swims; for the pupc'e of mosquitoes, and p"p^' also of certain midges, differ from the pupae of other insects in being active. The pupa state lasts only a few days ; then the skin splits down the back, and the winged mosquito carefully works itself out and cautiously balances itself on the cast skin, using it as a raft, until its wings are hardened so that it can fly away. The larvae of mosquitoes are doubtless beneficial insects, for they feed on decaying matter in water, and thus act as scavengers ; but the annoyance caused by the bites of the adult females more than counterbalances this good. The males of mosquitoes neither sing nor suck blood ; * they are said to feed on the sweets of flowers. These pests can be repelled by smoke and by certain strong-smelling substances. In regions where they abound it is customary to build smudges in the evening for this purpose ; and sportsmen anoint their faces and hands with aromatic ointments. The best of these is made of mutton tallow scented with camphor and oil of pennyroyal; a mix- ture of oil of tar and oil of pennyroyal is also used. It often happens that plagues of these pests are bred in receptacles of rain-water standing near dwellings; such re- ceptacles should not be left open unnecessarily. When the breeding-places are ponds of limited extent the larvae and *E. Ficalbi states that he has observed two Italian species in which both sexes suck blood. Bull. Soc. Ent. It
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectinsects, bookyear1895
