Succession saisonnière, émergence, voltinisme et répartition de mouches noires des Laurentides (Diptera; Simuliidae)

Abstract

A study of the distribution and the emergence of blackflies in 33 stations in streams at the Saint Hippolyte Biology Station gives the following dynamic picture: (1) The main emergence starts in May with the appearance of the univoltine species that have grown through the winter, followed by the first generation of spring-growing or summer-growing polyvoltine species. The predominance of the eurytopic univoltine species, mainly Prosimulium fuscum and Cnephia mutata, explains the presence of blackflies in nearly all the stations. (2) In July the second generation of the polyvoltine species appears, Simulium decorum, S. vittatum, S. aureum, S. verecundum, S. croxtoni, and S. vernum; these species lend to be more stenotopic, which restricts emergence mainly to stations near lake outlets; the other stations harbour only small populations of S. tuberosum. (3) The same distribution is evident in late August and early September when the third generation of the polyvoltine species matures, particularly S. tuberosum, S. aureum, and S. verecundum. A wet and cool summer tends to favour the development of large populations of blackflies.