Family: Hydrophilidae
Subfamily: Hydrophilinae
Length: 8-9 mm
There are several all-black species of Tropisternus that are difficult to distinguish to species without a pinned specimen.
In a 1958 study published in Ecology, Frank N. Young raised several species of Tropisternus in the laboratory. He reported:
- Coitus lasts a few seconds to a minute or more
- Females attach egg cases to aquatic plants
- All three instars of larvae feed readily on the larvae of mosquitoes and pomace flies
- Pupation takes place just above the water level, where the soil (sand) is moist but not saturated
- In the laboratory, adults experience high mortality when they are offered only algae to eat, but the addition of Haine's Dog Food to their diet causes the beetle population to flourish
- From coitus to emergence as adults takes 32 to 44 days, depending on the species of Tropisternus
