Spiny Crawler Mayflies
This common and widespread group includes roughly 80 North American species in 9 genera. Larvae can be readily identified, as this is the only mayfly group with gills absent on abdominal segment 2. They tend to be found in lotic-erosional or depositional habitats, often among the rooted aquatic plants, moss, root masses, or woody debris. They usually are poor swimmers, swimming with a floppy motion, and instead sprawl or cling to the plants or other substrates in their habitat. The family has a variety of feeding strategies, differing among species, including collector-gatherers, scrapers, some shredders of detritus or algae, and even one predator. When a larva is disturbed it sometimes raises its tail over its head like a scorpion, possibly as an adaptation to fend off predators; however, they cannot sting. After emergence, adults sometimes swarm atypically high, even above tree tops. This group is one of the most important for the fly-fishing community, with at least 30 different species being used as models for tied flies.