LATERAL DISPERSAL OF ADULT AQUATIC INSECTS (PLECOPTERA, TRICHOPTERA) FOLLOWING EMERGENCE FROM HEADWATER STREAMS IN FORESTED APPALACHIAN CATCHMENTS

We monitored the lateral dispersal of adult Plecoptera and Trichoptera following emergence from 4 headwater streams that drain adjoining for ested catchments on the Allegheny Plateau of West Virginia We assessed these dispersal distances to examine the lateral distance traveled by particular taxa and the variation in these distances among streams. T he number of adults captured decreased with distance from a stream for 16 of the 17 more common plecopteran and trichopteran taxa The 16 tar a had mean maximal lateral dispersal distances of from 44.1 m for Homo plectra monticola (Flint) to 81.4 m for Leuctra spp. These distances a re generally < 1/2 the median distance of 301 m between adjacent headw ater streams in this region. This suggests that direct lateral dispers al of adults among headwater streams may be relatively uncommon for ma ny species.