This is the largest aquatic-dwelling beetle in the United States, reaching over 1.5 inches in length. They range throughout North America and live in lakes and ponds with emergent vegetation. As larvae, they are capable predators, feeding on small invertebrates like insects and snails, but also tadpoles and small fish. Adults, despite their name, prey on animals, as well as scavenge decaying plant material and detritus. While adult beetles spend much of their time in or under water, they still need to breathe air. Handily, they can trap a bubble of air between their wings and abdomen, essentially creating a “scuba tank” that will let them stay under for long periods of time. This beetle was found on a forest road and was likely in search of a new area before it reproduces.
Photo by Kristi DuBois on 8/19/20 near Lolo, MT