Bug Bites #009 - Azolla Weevil (Stenopelmus rufinasus)
Family: True Weevil Family (Curculionidae)
IUCN Conservation Status: Unassessed
Ferns of the genus Azolla (commonly known as Mosquito Ferns or Water Ferns) are aquatic plants that live as free-floating rafts on the surface of slow-moving freshwater habitats, absorbing nutrients directly from the water through their long, frilly roots while a unique species of cyanobacteria living on their leaves provides them with nitrogen. Able to rapidly reproduce as new plants grow from fragments that brake off from their leaves Azolla species tend to dominate the surface of bodies of water in which they occur, and under ideal conditions the rafts of floating foliage they form can become so dense that they prevent other aquatic organisms growing under the water from accessing light. To this end, the Azolla Weevil is an essential-but-easily-overlooked part of many swampy freshwater ecosystems in its native range of North America; a highly specialised herbivore able to walk across the surface of water without breaking the surface tension, adults of this species both feed on Azolla ferns and lay their eggs in cavities chewed into the leaves, providing their larvae with shelter and food as they develop. In parts of Africa, Asia and Europe the popularity of Azolla ferns as ornamental pond plants has allowed them to become established as highly destructive invasive species, but in recent years the introduction of captive-born of Azolla Weevils has proven effective in keeping these invasive populations under control; owing to their own rapid reproduction a small starting population of Azolla Weevils can explode to immense numbers so long as their host is abundant, and as they feed exclusively on Azolla ferns it is unlikely that they'll cause wider ecological damage or persist after Azolla numbers have been depleted.
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