Life cycle of Simulium jenningsi (Diptera: Simuliidae) in southern West Virginia.

The life cycle of Simulium jenningsi Malloch was compared at two study sites representing the largest and smallest streams (New River and Indian Creek, respectively) where this species is known to breed in southern West Virginia. Larvae first appeared in March, and the first generation emerged in April, followed by two to four more generations by September. A few larvae and adults persisted in autumn, then the population overwintered in the egg stage. There were considerable differences in life cycle at the two study sites. In the New River, emergence of the first generation was 2-3 wk earlier, there were five generations rather than three, and the last larvae of the season persisted 1 mo later as compared with Indian Creek. Warmer temperature and higher quality food in the New River are probable explanations for differences in life cycle. Effective pest management of this species will require larviciding at frequent intervals (1-2 wk) from April through September in many streams over a broad geographic area because of the species' nonsynchronous life cycle, occurrence in different size streams, and strong dispersal ability.