(Synonym: Gad, or Bot-fly.)

Describe the cutaneous disturbance produced by the oestrus.

The ova are deposited in the skin, develop and give rise to the formation of furuncle-like tumors with central aperture, through which a sanious discharge exudes; or as the result of the burrowing of the larvÆ, irregular serpiginous lines or wheals are produced.

It is chiefly met with in Central and South America.

Larva migrant, or creeping disease, is doubtless in this same class. It is characterized by a thread-like linear formation of an erythematous, erythemato-papular, or vesicular nature that gradually extends, the older part disappearing; considerable surface may be covered before the parasite disappears or dies. The treatment consists in endeavoring to destroy the organism by means of excision or caustic applications at the point of its suspected site which is just ahead of the extending line.