Hydrilla
Guides
Bagous
Bagous is a genus of semi-aquatic weevils in the family Curculionidae containing at least 360 described species. Many species are associated with aquatic or semi-aquatic habitats, with several species developed as biological control agents for invasive aquatic plants, particularly Hydrilla verticillata. The genus includes both native and introduced species with varying degrees of host specificity. Larvae typically develop within plant stems while adults feed on stems and leaves.
Bagous restrictus
Bagous restrictus is a small weevil native to North America that has become notable for its exclusive association with the invasive aquatic plant Hydrilla verticillata. It is the only native Bagous species known to utilize this introduced weed as a host. The beetle completes its entire life cycle within Hydrilla tissues, with larvae feeding and developing inside stems and tubers. Its native status and host specificity distinguish it from two introduced biological control agents (Bagous hydrillae and B. affinis) that also target Hydrilla.
Parapoynx diminutalis
Hydrilla leafcutter moth
Parapoynx diminutalis is an Asian aquatic moth in the family Crambidae, first described from southeast Asia in 1880. The species has established adventive populations in North America (first recorded Florida 1976), Central America (Panama), Africa, and Europe (United Kingdom). Larvae are aquatic and feed on submerged macrophytes, with documented development on Hydrilla verticillata, Chara vulgaris, Ottelia alismoides, Blyxa auberti, and Cyperus rotundus. Despite early interest as a biological control agent for invasive hydrilla, its generalist feeding habits precluded intentional release.