Habitat and its structure as presupposition for an autochthonous development of areas with damage through blackflies (Diptera : Simuliidae).

Areas of damage through mammalophilous species of blackflies are specially always well defined. Critical examination is here made, to see if areas of long standing could be the point of origin of new areas with damage through blackflies. New areas could for instance arise through the migration of th e images or the drift of larvae in running waters. Images generally only un dertake exploritory flights within their particular river system, while the spread through drifting of the larvae is only very local, because of a res train to drift. The areas of damage arise autochthonously. Females recognis e, on the basis of certain structures, their specific egg laying places. Hu man actions, such as structuring of rivers and streams benefited and benefi t especially widely distributed potamale species, since such activities wid en the offer of the specific egg depositing locations, one of the condition s for the development of populations rich in individuals. For a differentia tion of areas of damage, the suggestion is made to apply the system of term inology applied to population dynamics.