Caterpillars, for example

• Caterpillars, e.g
• Some creepy crawlers
• Doodlebugs and polliwogs
• Young insects
• Future monarchs, e.g
• Bog area oddly contains river grubs
• Tadpole, caterpillar, etc.
• Grubs, e.g.

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)]

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Larva \Lar"va\ (l[aum]r"v[.a]), n.; pl. L. Larv[ae] (l[aum]r"v[ae]), E. Larvas (l[aum]r"v[.a]z). [L. larva ghost, specter, mask.] (Zo["o]l.) Any young insect from the time that it hatches from the egg until it becomes a pupa, or chrysalis. During this time ...