ENTOMOLOGY

V50SANITARY ENTOMOLOGYpart of each ring is much broadened and divided txansversely by a narrowsmooth space. On segments 5 to 10 there is on each side behind a fusiformswollen area pressing against the swollen ring of the next segment;this area also has spines. The tip of the body shows on the dorsal parta great cavity, in the bottom of which _!..!Le the stigmal plates, each withthree straight slits, those of one sub-parallel to those of the other;there is no button (fig. 30). Behind this cavity is a high, transverse,spiny cre'>t; and the ventral part of the tip shows an area covered withspines bearing two rather widely separated;prominent, smooth tubercles.The upper edge of the tip s.hows four small conical tubercles.PLATE IV.- ~crew worm injury to a yearling calf. (Bishopp.)The larva of this insect is called the "screw-worm," and occurs insores and wounds of domestic animals and also in man. There arevarious records of its presence in the ears and nose, or nasal cavities,of people; in swellings near the nose; in a boil under the arm; under theskin of a child; and in the navel of a child~ It is hardly a possiblefactor in intestinal myiasis of man, and most of such recorded casesprobably belonged to some species of Sarcophaga whose larvre are verysimilar in appearance to those of the screw-worm.SarcophagidaeThe Sarcophagidae have two great hooks, and the posterior stigmalplates have three slits as in Calliphora el'ythrocephala and Lucilia seri-