The Argasidae

Subfamily: Argasinae

Argas walkerae and Argas persicus - The fowl tick or fowl tampan

The ticks are flat and their outline egg-shaped (ovate). The capitulum of the adults and nymphs is present on the antero-ventral surface of the body and not visible from above. The integument of the body is leathery and on both the dorsal and ventral surfaces there are numerous symmetrically arranged discs. The margin of the body is sharp, clearly defined and differentiated morphologically from the rest of the integument by a row of quadrangular cells on both the dorsal and ventral surfaces. Eyes are absent.

It infests domestic fowls, ducks, geese and turkeys. The female tampan lays a batch of 20 to 100 eggs after each blood meal. The eggs hatch in approximately 3 weeks. The six-legged larvae will attach and feed on a host for five to 10 days, usually under the wings. They drop off to moult in cracks and crevices in the poultry house. The nymphs will feed for 5 minutes to a few hours and then moult. There can be 4 nymph stages each requiring a blood meal before moulting to the next stage. Moulting to the adult can occur from the 2nd stage onwards. The final nymph stage moults to the adult which also feeds for a short while and like the nymphs usually only at night when the birds are roosting. The adults feed about once a month and the females produce a batch of eggs after each blood meal, they may produce some six or seven batches during their lifetime. The larvae can survive for 2 months or more, the nymphs for 1 year and the adults for up to 3 years without a blood meal. Very large populations of ticks can build up rapidly in untreated poultry houses.

Larvae and the first nymphal stage in early summer; nymphal stages 2 to 4 are present in midsummer; adults late summer and winter. The ticks over-winter as adults or eggs.

The two Argas spp. can transmit a number of diseases to poultry (e.g. avian spirochaetosis and piroplasmosis). The larval ticks excrete a toxin causing paralysis in chickens and in ducks.