. Special report on diseases of cattle . Cattle. 498 DISEASES OF CATTLE. Buffalo gnats are more troublesome in bright, sunny weather than when it is cloudy, and animals which have not shed their winter coats suffer more from their attacks than those with smooth coats. Cattle kept in darkened stables are not molested. The application of one of the fly repellants already mentioned (p. 495) will help to protect animals from buffalo gnats. The burning of smudges is also a useful means of protecting stock from the attacks of these flies. Screw "Worms. Screw worms (fig. 6) are the mag- gots of
. Special report on diseases of cattle . Cattle. 498 DISEASES OF CATTLE. Buffalo gnats are more troublesome in bright, sunny weather than when it is cloudy, and animals which have not shed their winter coats suffer more from their attacks than those with smooth coats. Cattle kept in darkened stables are not molested. The application of one of the fly repellants already mentioned (p. 495) will help to protect animals from buffalo gnats. The burning of smudges is also a useful means of protecting stock from the attacks of these flies. Screw "Worms. Screw worms (fig. 6) are the mag- gots of a fly (Chrysomyia macellaria), so called from their fancied resem- blance to a screw. The adult fly (fig. 7) is about one-third of an inch long, with a bluish-green body, red eyes, and with three dark longitudinal stripes on the back (thorax). At-. FiG. 5.—Buffalo gnat. (Prom Bureau of Entomology.) Fie. 6.—Screw worm (larva of Chrysomyia macel- laria). (From Bureau of Entomology.) tracted by odors of decay it deposits its eggs, 300 to 400 at a time, in cuts, sores, castration wounds, etc. The bursting of a tick on the skin com- monly results in screw-worm infec- tion at that point. The eggs hatch in a few hours and the larvae or maggots, or so-called screw worms, begin to burrow into the flesh and continue burrowing and feeding from four to six days, after which they leave the wound and crawl into the eai^th, there transforming into the quiescent pupal stage. After this stage has lasted for one to two weeks, the mature fly appears. From two to three weeks are therefore required for the entire life cycle. Besides cattle, the screw-worm fly attacks sheep, horses, hogs, and man. In the case of hogs it is generally the ears which are Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original United States. B
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