Rachel’s kids found this larva in their pond and were curious as to what it was. They described it as being approximately 3.78 inches long and aggressive. Aggressive was an appropriate adjective, as predaceous diving beetles are known as water tigers in their larval stage, feeding on aquatic invertebrates like mosquito larvae, as well as tadpoles, salamanders, and small fish. It’s possible for them to give you a good pinch if handled. Based on the size of the larva, this may be a Giant Green Water Beetle. Adults are active predators and scavengers and swim by moving their flattened legs in unison like oars. They have a neat trick for breathing underwater — they collect air at the surface in a “bottoms-up” pose, trapping a bubble beneath their wing covers. They can fly too, although if they become stranded on land they cannot crawl well.
Photo by: Rachel Somers on 7/12/21 in the Bitterroot Valley, MT