. Injurious and useful insects; an introduction to the study of economic entomology. Insects; Beneficial insects; Insect pests. THE WARBLE-FLY 151 becomes deeply wrinkled, while the warble-cavity gets a special wall, derived from the connective tissue of the ox. The larva has no limbs, and only a vestige of a head, which is ordinarily retracted into the body. A pair of forks, answering to the hard and pointed hooks of the blow-fly larva, can be protruded from the mouth - opening. The prominent transverse ridges of the body bear broken rows of small hooks, and it is by means of these that the m
. Injurious and useful insects; an introduction to the study of economic entomology. Insects; Beneficial insects; Insect pests. THE WARBLE-FLY 151 becomes deeply wrinkled, while the warble-cavity gets a special wall, derived from the connective tissue of the ox. The larva has no limbs, and only a vestige of a head, which is ordinarily retracted into the body. A pair of forks, answering to the hard and pointed hooks of the blow-fly larva, can be protruded from the mouth - opening. The prominent transverse ridges of the body bear broken rows of small hooks, and it is by means of these that the maggot executes such limited movements as are indispensable. In the middle of the flattish surface which ends the body are two dark spots; these are the spiracles; they lead into longi- tudinal air-tubes, which supply every part of the pjg^ of body. The body is always so placed that the warbie - fly. After spiracles are directed towards the opening of ^^'^'^ the warble cavity. Just beneath the spiracles is the outlet of the alimentary canal. In the next summer, the maggot, being now nearly a year old, is about 35 mm. long, fat, wrinkled, and of a leaden or deep-brown colour. It squeezes through the skin, and falls to the ground, where it passes the next few weeks, with only such slight protection as it can get by hiding in a crevice or beside a stone. Its skin contracts, hardens, and acquires a deeper colour. The body becomes flat and then concave along one side, towards which both head and tail are directed. The transformation to a pupa is completely hidden, as in the blow- fly, by the retention of the larval skin, which acts as an ex- ternal shell or cocoon. After four or five weeks on the ground, the dry skin cracks near the head, a circular cap surrounding the detached, and the fly escapes. The fly is seldom seen, except when it is reared from a captive pupa; it is only about 13 mm. long. In most points of structure it re- sembles the blow-fly, but is
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectinsects, bookyear1902
