It has been asserted by Haller that the Cape ailment (Port Natal sickness) is caused by mites, but this statement has been contested.
Tetranychus telarius, L., 1758,[335] var. russeolus, Koch.
Fig. 352.—Tetranychus telarius var. russeolus, Koch. Enlarged. (After Artault.)
This common spinning mite likewise attacks human beings, but the papules produced by it very soon disappear.
Family. Tarsonemidæ.
A family distinguished by complete sexual dimorphism, the species of which are provided with tracheæ; the legs have five segments; the terminal segments of the front pair of legs of both sexes possess a claw; the terminal segment of the posterior pair of legs of the male likewise has a claw. In the female this pair of legs, like the second and third pairs of both sexes, is provided with two hooklets and a sucking disc. The cuticle of the body on the back is “annulated.”
[This family of small transparent mites live normally as plant parasites. The last two pairs of legs are widely separated from the two front pairs.—F. V. T.]