Nineteen Ontario species were studied and five from outside Ontario examined. Newly emerged females were of five types: with (1) mature eggs and reduced mouth parts (Gymnopaïs spp., Cnephia spp.); (2) eggs half developed, much stored nutrient, and reduced mouth parts (C. emergens, P. alpestre); (3) eggs half developed, much stored nutrient, and piercing mouth parts (C. mutata); (4) eggs one-fifth to one-third developed, usually much stored nutrient, and piercing mouth parts (Simulium spp.); (5) eggs less than one-quarter developed, little stored nutrient, and piercing mouth parts (Prosimulium spp., Simulium spp.). In Cnephia spp. (type 1) mating occurred shortly after emergence with little flying. In C. mutata parthenogenesis is usual. Male mating flights occurred in species of Prosimulium and Simulium. But S. decorum mated on a support shortly after emergence and also just before oviposition. C. mutata fed infrequently on deer. Occasional females of S. decorum and S. vittatum (type 4) fed on mammals. Species of type 5, S. croxtoni, S. euryadminiculum, S. latipes, and S. rugglesi fed only on birds, S. venustum naturally on birds and mammals, and others naturally only on mammals. Ovarian development in species of types 4 and 5 took live or more days. In those of type 5 it began only after a blood meal that may take two weeks to acquire. Females of Prosimulium, Cnephia, and some Simulium species dropped eggs into the water while flying. Other Simulium species oviposited on water-covered surfaces either while flying or alighted, depending on conditions. Oviposition was greatest in the evening but occurred at other times when populations were large, and conditions favorable.
The 33 species of Prosimulium Roubaud known from Canada and Alaska are reviewed. These are segregated into four subgenera: Distosimulium new subgenus, containing one species; Parahelodon new subgenus, containing three species; Helodon Enderlein, containing seven species of which clavatum, martini, and susanae are new, and one (known only from the larva) remains undescribed; Prosimulium s. str., containing 25 species of which approximatum, constrictistylum, impostor, mysticium, neomacropyga, and woodorum are new. Species of the last subgenus are segregated into three species groups. A lectotype is designated for P. ursinum (Edwards). Descriptions, distribution maps, keys, and 158 illustrations for the identification of the known adults, pupae, and larvae are provided.
Ten new species of Trichobius are described from the Neotropical Region: T. intermedius (Dominican Republic, Haiti, Bahama Islands, Cuba, Jamaica, Puerto Rico, Virgin Islands, Lesser Antilles, Mexico, Guatemala, Honduras, and El Salvador); T. neotropicus (Dominican Republic); T. cognatus (Dominica and Cuba); T. wenzeli (Cuba); T. dusbabeki (Cuba); T. cernyi (Cuba); T. frequens (Cuba, Dominican Republic, and Jamaica); T. macroti (Cuba and Bahama Islands); T. robynae (Puerto Rico); and T. dominicanus (Dominican Republic).
Insect predators of black flies are common although their predatory acts are infrequently observed. Observations are presented on black-fly predation by various species of the dipterous families Empididae, Dolichopodidae, Ephydridae, and Tendipedidae. A case of cannibalism among larvae of Simulium venustum is reported. Other insect predators of black flies mentioned include various species of Trichoptera, especially species of the genus Hydropsyche; Hymenoptera; and Odonata. Non-insect predators of simuliids that are mentioned include spiders, and a leech, Haemopis marmorata (Say). In Algonquin Park, Ontario, larvae of species of the trichopteran genus Hydropsyche appeared to be the most important predators of simuliid larvae, while dance flies were the most important predators of adult black flies.
Immature and adult black flies are often victims of various predatory or parasitic organisms. Observations on certain of these organisms were made in Utah over a period of several years, and are presented below to stimulate further interest in the natural enemies of the Simuliidae.
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