FACTORS INFLUENCING NUISANCE BLACKFLY (DIPTERA, SIMULIIDAE) ACTIVITY IN THE SCOTTISH HIGHLANDS

The nuisance activity of blackflies (Diptera: Simuliidae) was investig ated in several habitats on Speyside, near Kincraig (57-degrees-08'N. 3-degrees-56'W), Invernesshire, in central Scotland during May-October 1987-89. The main blackfly species caught landing/biting on humans we re Simulium reptans, S. argyreatum, S. variegetum and the S.tuberosum complex, in order of prevalence. Blackfly biting activity occurred fro m mid-May to mid-September. Numbers of female blackflies attracted to volunteers were correlated with their body posture, habitat and the se ason. Overall, Simulium activity was greatest in mixed birch/juniper f orest, least in spruce plantations and at intermediate levels on pastu re, moorland and in Scots Pine forest. Compared with an adult, a child experienced twice as many Simulium bites per hour (12.2 v 6.3) in the birch forest. On the child's body, 69% of blackflies landed on the he ad, neck and back, whereas the majority landed on the legs (48%) and a rms (28%) of adults. Bending over, especially during the exertion of g ardening, was more attractive to anthropophilic blackflies than standi ng or kneeling.