Definition of caseworm in US English:

caseworm

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.

Pronunciation

caseworm

/ˈkeɪswəːm/