The biology of nineteen taxa of African Stomoxyinae was studied during
experiments with odour-baited Vavoua traps in Nairobi National Park,
Kenya. Both male and female Stomoxys were captured in similar numbers
with CO2 released at 2 l/min or octenol released at 2 mg/h. Some speci
es of Haematobosca reacted synergistically to a combination of these t
wo attractants, producing large increases in catch. Stygeromyia and Rh
inomusca responded only to CO2, and Prostomoxys did not respond to eit
her bait. Many different activity patterns were documented in these ge
nera, but most activity was concentrated just prior to sunset. For exa
mple, at peak densities nearly 1500 Stomoxyinae representing fourteen
taxa were caught in a single trap between 18.00 and 19.00 hours. The S
tomoxyinae community was exceptionally diverse when compared with othe
r biting fly communities. Using data from traps set with different odo
ur baits in the park forest, Shannon-Wiener diversity indices (H') var
ied from 2.5 to 2.8, and evenness (J') varied between 0.61 and 0.68. T
he Stomoxys population was extremely female-biased at the start of the
rainy season, with species such as S.inornatus and S.boueti consistin
g of nearly 100% females. Sex ratios equalized when the first rainy-se
ason generation emerged. Population doubling times estimated from trap
indices were approximately 12-16 days in two habitats (forest and riv
erine woodland).