If you live anywhere near one of these occurrence points, then you’re in Gymnusa country. And this is a good thing because I’m on the lookout for specimens for molecular studies.
Gymnusa live near stagnant bodies of water in the cooler parts of the Holarctic. They are most commonly encountered in bogs, fens, swamps, and ponds. Some appear to prefer spruce or alder swamps.
The general key to collecting them is to tread on vegetation that grows out of the water down into the water, submerging the above-water growth, weather this be a reedy plant like Carex or Sphagnum moss. This will chase the beetles out from the matrix of vegetation. Beetles that leave this way can be found floating on the surface of the water.
These are some typical habitats for Gymnusa species.
The video was taken at a swamp in Vermont (the habitat photo on the left). I call this the Gymnusa Dark Ages, sneakers with no socks, before my super awesome waders.
Here’s another video, this one of an adult Gymnusa atra feeding. Needless to say, both of these subjects have never been filmed before to my knowledge.