Why is the ninth month called September?
1650s, "a ghost, specter," from Latin larva (plural larvae), earlier larua "ghost," also "mask;" applied in biological sense 1768 by Linnaeus because immature forms of insects "mask" the adult forms. On the double sense of the Latin word, Carlo Ginzburg, among other students of mythology and folklore, has commented on "the well-nigh universal association between masks and the spirits of the dead."
larva lar·va (lär'və)
n. pl. lar·vas or lar·vae (-vē)
The newly hatched, wingless, often wormlike form of many insects before metamorphosis.
The newly hatched, earliest stage of any of various animals that undergo metamorphosis, differing markedly in form and appearance from the adult.
Plural larvae (lär'vē) or larvas