Field observations on the life cycle of Ixodes baergi and some seasonal and daily activity cycles of Oeciacus vicarius (Hemiptera: Cimicidae), Argas cooleyi (Acari: Argasidae), and Ixodes baergi (Acari: Ixodidae).

Abstract

Observations were made at a Cliff Swallow colony in Texas during the nesting season on aspects of the natural history of Oeciacus vicarius Horvath, the swallow bug; Argas cooleyi Kohls & Hoogstraal, the swallow tick; and Ixodes baergi Cooley & Kohls. Each of the parasitic life stages of I. baergi was collected from both adult and nestling Cliff Swallows, Hirundo pyrrhonota (Vieillot). It appears that in I. baergi the larva is the overwintering stage, that most larvae and nymphs feed on adult birds before nestlings are present, and that nestlings are hosts of the adult female ticks. Adult male I. baergi were never found on a host or in copulo with a female, but they were occasionally collected from the wall of the culvert where the Cliff Swallows nested. Engorged female I. baergi have a detachment rhythm, with the peak number of the females (54.2%) detaching between 2200 and 0400 hours (CST). Although some A. cooleyi were seen earlier, numbers observed increased markedly after swallows began to hatch and decreased abruptly the week before the first birds fledged. In contrast, peak activity of the O. vicarius occurred the week the colony was abandoned, and 2 wk later sizeable numbers of swallow bugs were still active. O. vicarius and A. cooleyi have nocturnal activity rhythms; swallow bug activity peaked between 2200 and 0100 hours, and that of the swallow ticks between 2400 and 0600 hours.