A comparative study of the biology of five species of Neophylax (Trichoptera: Limnephilidae) in southern Ontario

Abstract

The habitat, life cycle, behaviour, and food of five species of caddisflies of the genus Neophylax (N. aniqua Ross, N. ornatus Banks, N. concinnus McLachlan, N. oligius Ross, and N. fuscus Banks) were compared, based on general surveys and biweekly to monthly samples from several stream systems in southern Ontario. Larvae of four of the species, N. aniqua, N. concinnus, N. oligius, and N. fuscus, occur sequentially from the headwaters downstream and grow from late autumn through spring, but differ slightly in temporal development; adults of these species emerge in September and October, after a summer prepupal diapause. Larvae of the fifth species, N. ornatus, grow in late summer and autumn; their habitat coincides with portions of the habitats of N. aniqua and N. concinnus in cool headwater sections of streams, but adults emerge in June following a winter diapause. These species also differ in duration of diapause, case construction, location of pupal cases, and oviposition. All species graze on algae and fine organic particles from exposed surfaces of rocks. The study demonstrates that the five species of Neophylax studied differ in larval habitat and in time of development in ways that tend to keep them separate in stream systems. Evolutionary implications are considered.