Entomological term for the immature stage of hemimetabolous insects, resembling the adult but lacking fully developed wings and reproductive organs.
See also: ニンフ
Dragonfly nymphs live in water.
Grasshopper nymphs resemble adults but have short wings.
Compound of 若 (waka, 'young') and 虫 (mushi, 'insect'). The reading わかむし is a straightforward kun'yomi combination.