Drawings of a larval and an adult predaceous diving beetle can be seen at this water bug site . Whirligig beetles, Dineutus species, are some of the funniest insects to show up at my ponds. The adults act like they have had too much too drink and spin around in the water. The 0.5 to 1 inch adults are scavengers and can see above and below water at the same time. Their front legs are long.
Adults eat dead plants and animals and insects.
The larvae, on the other hand, eat whatever animals they can catch and have more noticeable filaments than legs. Larvae are 0.8 to 1 inches long and crawl along the bottom. Larvae may eat insects, snails, and mites. Drawings of a larval and an adult whirligig beetle can be seen at this water bug site . Some eat animals, and some eat plants.