This is the world's most species-rich stonefly family including 84 North America species and almost 1,000 worldwide. The generally black-and-yellow-striped larvae are often found clinging to substrate in riffles and other lotic-erosional habitats. Young larvae tend to collect and gather small amounts of food until they are large enough to engulf their prey, including caddisflies, midges, and other small invertebrates. Some of the larvae are territorial, swinging their cerci (tails) at other animals that get too close. If not enough oxygen is present in the water, they can be seen doing strange push-up-like movements in order to move more water across the gills. A life cycle can require from 1–3 years, depending on environmental conditions. They emerge as flying adults in spring and summer, and can often be drawn to lights at night.
Mid-Atlantic: 0 - 2
Upper Midwest: 0 - 5
Midwest: 1.8 - 4.5
Southeast: 0 - 4.9
Engulfer / Predator
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Order: Wings developing in wing pads. Mouthparts suitable for chewing. Gills digitiform and located near mouthparts, on neck, sides of thorax, or underside of base of abdomen, never on top or sides of abdomen. Two tarsal claws per leg. Only two tails (cerci).
Family: Glossae much shorter than the paraglossae. Multi-branched, filamentous gills present laterally and ventrally on thorax, but not on abdomen.