Hydrophilus

Hydrophilus is a genus of aquatic beetles belonging to the family Hydrophilidae, commonly known as water scavenger beetles. These insects are characterized by their large, robust bodies and distinctive antennae. They are found in freshwater habitats worldwide, including ponds, lakes, and slow-moving streams, where they often inhabit areas with abundant aquatic vegetation.

Adult Hydrophilus beetles are primarily scavengers, feeding on decaying organic matter, algae, and dead invertebrates. However, they can also prey on small aquatic animals. Their larvae are predatory and are known to consume tadpoles, snails, and other small aquatic organisms. Both adults and larvae possess respiratory siphons that allow them to breathe air at the surface of the water.

A notable feature of Hydrophilus is their ability to produce a defensive secretion from glands near their hind legs. This secretion can deter predators. Many species are quite large, with some individuals exceeding several centimeters in length, making them among the largest beetles found in freshwater environments. Their presence in an aquatic ecosystem can serve as an indicator of water quality, as they generally prefer habitats with relatively clean water. Reproduction involves the deposition of egg cases, which are often attached to aquatic plants.