Blake and Ollie found this sizable critter in a parking lot in Helena. We were happy to inform them that they had found a Predaceous Diving Beetle (in the genus Dytiscidae). Based in its size and appearance, we’re pretty sure this is a Harris’s Diving Beetle (Dytiscus harrisii). While predaceous diving beetles breathe air, they can remain underwater for long periods of time by trapping a bubble of air between their wing covers (elytra) and abdomen, creating a DIY SCUBA tank. Along with their impressive larvae (commonly called water tigers), the adults are typically found in water. However, adults will sometimes fly off in search of new waters and are unfortunately attracted to lights – the reason this fellow was discovered in a parking lot where lights are on all night.
Want to learn more? Check out our Bug Bytes podcast about Predaceous Diving Beetles here!
Size: 1.25 to 1.5 inches
Photos by: Blake and Ollie on 7/13/22 in Helena, MT
