Family. Gamasidæ (Coleopterous or Insect Mites).
Cheliceræ chelate or styliform; pedipalpi filiform; the legs are composed of six segments with two terminal ungues and a bladder-like sucking disc [caruncle—F. V. T.]. Stigmata situated between the third and fourth pairs of legs; the cuticle thickened, leather-like; no eyes; the larvæ have six legs.
The Gamasidæ are predaceous on small insects and other mites; some are parasitic on insects, and one is noticeable as a pest on birds, etc.
Genus. Dermanyssus, Dugés.
Dermanyssus gallinæ, de Geer, 1778.
Syn.: Pulex gallinæ, Redi, 1674; Atarus gallinæ, de Geer, 1778; Dermanyssus avium, Dugés, 1834.
The male measures 0·6 mm. in length by 0·32 mm. in breadth; the female 0·7 to 0·75 mm. in length by 0·4 mm. in breadth. The body is somewhat pear-shaped; the colour whitish, reddish, or reddish-black, according to the contents of the intestine. The legs are fairly short and strong. During the day they live concealed in the nests, cracks, etc., of the hen-house, and at night attack the inmates in order to suck their blood; they rarely remain long on the birds. They have been repeatedly found on persons, on whose skin they produce an itching eruption.
