Bog area oddly contains river grubs

• Grubs, e.g.
• Nymphs line a rave dancing?
• Young eels
• Immature forms
• Second of Variations Ravel composed for 16 17A?
• Insect stages
• Young insects

Wiktionary Word definitions in Wiktionary
n. (en-irregular plural of: larva)

WordNet Word definitions in WordNet
n. the immature free-living form of most invertebrates and amphibians and fish which at hatching from the egg is fundamentally unlike its parent and must metamorphose [also: larvae (pl)]

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
plural of larva (q.v.).