Nigerian blood-fed blackflies (Diptera. Simuliidae) caught in flight: relative activity and host preferences.

Using a vehicle-mounted net, over 1000 blood-fed blackflies were collected in flight, showing that they had a much higher level of activity during this stage than was previously expected, particularly in Simulium squamosum. Activity was greatest in blood-fed females with Stage IV eggs, presumably because they were starting to search for oviposition sites. S. squamosum, S. adersi and S. vorax showed a moderate level of activity in flies with Stage II and III eggs, although these are normally considered to be resting stages. Blood-fed flies with Stage I eggs were relatively rare. Analysis of 601 blood meals showed that S. hargreavesi, S. squamosum and S. vorax were primarily cattle-feeders, although a few S. squamosum had fed on man (showing that this species has a high level of zoophily in this area). The few S. adersi, S. hirsutum and S. nigritarse collected had fed mainly on birds.