Page:The Zoologist, 4th series, vol 4 (1900).djvu/370

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In the 'Journal of the South-Eastern Agricultural College,' Wye, Kent, No. 9, issued in April last, Mr. F.V. Theobald has contributed an instructive article on "Diseases caused by Horse Worms and their Treatment." The following appear to be the major pests to the Horse:—

Amongst insects the Horse has several foes, including four species of Bot Flies. One of these flies, so far unidentified, forms warbles or tumours under the skin, like the Ox Warble. Probably this is Hypoderma silenus, but it is by no means common in this country; Mr. Theobald only remembers having seen one Horse attacked by it. The other Warble Flies live as parasites in their larval state inside the stomach and intestines (Gastrophilus equi, G. hæmorrhoidalis, and G. nasalis), where the bots cause annoyance and loss of condition, but seldom death. Lice of three species also annoy Horses turned out to grass, namely, the piercing-mouthed Hæmatopinus macrocephalus, or the Large Horse Louse, and two smaller species related to the Bird Lice, known as Trichodectes pilosus and T. pubescens, the former being the one most frequently seen, and is one of the three causes of that disfiguring rubbing of the tail. Numerous Diptera, such as the Gad Fly (Tabanus bovinus and T. autumnalis), Brimps (Hæmatopoda pluvialis), and others, suck their blood; whilst the Forest Fly (Hippobosca equina) causes annoyance in a few localities by tearing the hair and irritating the skin generally.

The three forms of "scab" or "mange" are also found on the Horse, caused by Sarcoptes scabiei v. equi, Psoroptes communis v. equi, and Symbiotes communis v. equi, mainly on weakly and ill-kept stock.

Amongst the vermiceous pests of the Horse we find representatives of the three great groups: Cestoda, or Tapeworms; Trematoda, or Flukes; and Nematoda, or Round Worms; but in this country the two former are rare and comparatively unimportant, for the loss they account for is slight. On the other hand, the Nematoda, or Round Worms, often are the cause of serious mortality, especially in young animals.

The Tapeworms found in the Horse are Tænia perfoliata, T. mamillana, and T. plicata. All three are uncommon, and do not seem to have occasioned any loss, nor do they seem to cause much inconvenience to their host. The two first-named species live in the intestines, but T. plicata is