Megaloptera - the dobsonflies, alderflies, and fishflies


Art by: C. Ruth Neudahl
Text by: Valerie Brady

Note the size of the real penny and use it to judge the size of the bugs in the following pictures.

Family: Corydalidae and Sialidae

larval Corydalidae

Class: Insecta

Order: Megaloptera, dobsonflies, alderflies, and fishflies

Family: Corydalidae and Sialidae

Size: Corydalidae: larvae: 1-3.5 inches (25-90 mm), adults: 2-3 inches (50-75 mm); Sialidae: larvae: 0.5-1 inch (10-25 mm), adults: about 0.75 inch (20 mm)

Habitat & Habits: Megaloptera larvae are common in streams and rivers, especially in riffle areas. The filaments ("spines") down their sides help larvae get oxygen from the water. Larvae cling and crawl through rocks, they are quick, strong crawlers and can swim forwards or backwards by undulating their bodies. Corydalidae larvae are called hellgrammites by fisherfolk and are prized bait. Adults are terrestrial; they have 4 wings but are poor fliers and crawl as often as fly. Adults are typically found along stream margins and live only a few days.

Feeding: Larvae are voracious predators and (WARNING) will bite humans. Adults probably do not feed.

Water Quality Indicator: Corydalidae larvae are very intolerant of pollution and are very good water quality indicators. Sialidae larvae are moderately intolerant of pollution.