The spiny water flea (Bythotrephes cederstroemi) is not an insect but a crustacean with a long, barbed trail. They are small and transparent, making it difficult to see them unless they occur in very large numbers.
Spiny water fleas have been found in Lake Superior waters at Isle Royale, but the park is trying to keep them out of inland lakes, which are among the most pristine waters in North America. Visitors to the park can help keep our inland lakes free of spiny water flea by following a few simple procedures:
Last updated: October 10, 2019