The Water Penny larva is a remarkably flattened, oval, copper-brown beetle larva that adheres to rock surfaces in fast streams, looking exactly like a small, round penny. Its flat shape reduces drag in strong current and allows it to scrape algae from rock surfaces. When conditions are right, adults emerge as small brown beetles and live briefly near streams.
Habitat
Undersides of rocks in fast, clean streams and rivers
Diet
Larvae: algae scraped from rock surfaces. Adults: do not feed
How common
Common
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