Behavioral-polymorphism
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Macrostemum carolina
Macrostemum carolina is a net-spinning caddisfly in the family Hydropsychidae. Larvae construct silken catchnets within protective retreats to filter food from flowing water. Multiple retreat-building phenotypes exist within this species, including retreats with water entrance holes at the end of silken tubes, with 180° silken backstops, or flush with the retreat top. Molecular genetic analysis confirms these phenotypes represent a single panmictic population rather than cryptic species.