Damalinia equi: Biting louse of horses

General Description: The adult lice are 1 to 2 mm. long. The head is broad and flat, with mouth parts adapted for chewing skin and hair. The wingless body is flattened dorsoventrally.

Life Cycle: All stages of the louse life cycle, which takes about 3 to 4 weeks, occur on the host. Louse eggs, cemented to animal hair, hatch to nymphs, which are small, immature adults. The nymph moults three times before becoming an adult. Lice are host-specific.

Location: Damalinia is usually found on the neck and at the base of the tail but may cover the whole body in heavy infestations.

Geographical Distribution: Worldwide where horses are raised.

Significance: Infestation with lice can be seriously debilitating.

Effect on Host: Damalinia bites cause skin irritation and itching. Infested horses will rub, scratch, and bite themselves, with resultant rough coats, skin infections, and loss of hair. Heavy infestations may cause general unthriftiness and weight loss.

Diagnostic Information: Identification of lice found on the coat and skin.

Control: Infestations are heaviest in late winter and early spring, when horses are in close contact and have heavy hair coats. Sanitary conditions and treatment with an organophosphate compound are important in control.

Damalinia– female