Berosus is a hydrophilid beetle with an easily recognised larva that has tentacle-like gills along the abdomen. As in other hydrophilids the larval head is often tipped backwards, and it has long sickle-like jaws. The adults are active swimmers with a generally oval, 5-segmented abdomen. The 7-segmented antennae have three enlarged segments at the tip (but these are often tucked under the head).
Berosus can be found in weedy and stony, streams and ponds.
The larval mouthparts suggest they are predators, but the adults may also scavenge on streambed detritus.
Hydrophilids occur in slow flowing waters with moderate to good water quality. The genus has a tolerance value of 5 (hard bottom sites) but there is no soft bottom value (though the family soft bottom value is 8).