Black fly host location: a review

Host location in black flies (Diptera: Simuliidae) is treated broadly as any event or action in the insect's adult life that (i) contributes to its ability to respond to a host, (ii) enhances its probability of contacting a host, or (iii) brings it into closer physical proximity to its ultimate goal, a blood meal. Host location in this broad sense is discussed under the following three headings. (i) Postemergence activities, such as nectar-feeding, mating, dispersal, and migration. These prepare the insect behaviourally and physiologically and bring it into the host's habitat, (ii) Host-searching, nonoriented flight driven by appetitive internal forces, namely endogenous activity rhythms and hunger. The host search maximizes the probability of contact with a host while minimizing energy output. (iii) Host location proper, oriented by external stimuli interacting with internal programmes of behaviour. Host location (sensu stricto) consists of long-, middle-, and short-range phases as well as postlanding activities, and is driven by olfactory, visual, anemotactic, optomotor, thermal, and gustatory stimuli. The paucity of information related to black flies for some of these topics is partially compensated for through extensive referral to the literature on similar problems in other insects.