SCAB IN SHEEP.

Patea Mail, Volume V, Issue 464, 4 October 1879, Page 3

SCAB IN SHEEP.

. [Continued from last issue.] ACARUB. Appearance.—When seen •with the naked eje, at rest in, the wool, or on the skin of the sheep, the live insect appears like a minute whitish round speck or object. The naked eye can in good light .also generally detect a brownish appearance at one end of the object, as well as the glistening pearly appearance which is so noticeable in examining the insect with the glass, and which is generally the first thing to attract attention when searching for it in that way. In a good light, the brown anterior legs and suckers of the insect can be seen with the naked eye, if it be placed in an •active state on a favourable surface—• •such as the blade of a knife, a peice of paper or glass,'or on the finger nail; ■and'the legs and. suckers may at times, under similar circumstances, be also observed in motion in the wool, as the insect’crawls from one fibre to another. The dead insect presents much the same appearance to the naked eye as it does while alive, and in a state of rest ; but when dead, it soon loses its plumpness, =and looks more or less shrivelled up, according to the time it has been dead ; its body, too, becomes duller and darker, while the brownish color of the head and •anterior legs seems to increase, and the •milk-white pearly appearance disappears. Under a good scab glass, the live insect if mbving or moderately lively, looks dike a diminutive crab, somewhat longer than it is broad, with a glistening or pearly milk-white plump body, and a small head, from which two suckers appear to protude. The head and suckers are of a brown color, as are also the legs, •one of which appears to be attached to •each sbolder, and one to. each side of the •body near its posterior extremity. Detection—Although scab in sheep may be unmistakably recognised by the symptoms which have been noticed above, the insect should in every case where the disease is active be demonstrated, and it is generally easily found. The readiest -mode of doing so is to plnck a lock or to from the fleece, at the edge of n green patch of scab, or of a patch where the disease is comparatively recent, and subject the wool thus plucked from the fleece, in a good light (in the snn, and holding it up), to a close scrutiny with the naked •eye, gently palling the wool apart as the examination proceeds, when the inject, if present, will be detected in the the minute speck or object already described! Where a scab glass or magnifier cannot be obtained, there are several ways of ascertaining whether or not the object noticed be an insect. The first thing is to get it from the wool, and this may be done by picking it out with the blade of a penknife, slightly moistened •sons to cause the speck to adhere to it, and gently moving the object along and away from the fibre. If the day be hot, and the speck be a living insect, it will, ■on being allowed to remain on theknife, make for the under or sdadowy side of the blade.

Where the insect cannot be readily detected with the naked eye in a lock of wool plncked from the affected part, it can with care invaribly. be so on - the skin or at the roots of the wool, at or near the diseased patch, and in searching for ■ it there,, after having in the first place examined the diseased or green portion of the patch, the wool should be laid open at right angles to, and for four or

ffve inches from its outer edge, and the roots of the wool and skin along thu lines thus exposed should be,subjected to a careful scrutiny, when if tl\e insect be present, it can be picked np with a knife or pin. This is a good plan to adopt tor another reason: patches of scab which do not exhibit any outward sign of their existence are thus exposed, and the course and extent of .the disease more fully traced. The acarns when present can thus generally be detected with the naked eye, but it is sometimes necessary to use a scab glass of a moderately large field to find it, especially : in. cold weather, when the insect willbe fopnd at the toots of the wool, or, perhaps partially; buried in the scab or scurf. Where, therefore, a search with the naked, eye is unsuccessful, the examination should in every case be continued with the jn the wool both on and off the sheep, a nd on the skin. To be continued!.)