caseworm
/ˈkeɪswəːm/noun
More fully paddy caseworm, rice caseworm. The aquatic caterpillar of the pyralid moth Nymphula depunctalis, which is a major pest of rice in South and South-East Asia, feeding on leaves and forming a protective case from their fragments.
Origin
Mid 16th century (in an earlier sense). From case + worm.