Plural of “larva”

The plural of larva is larvae (some dictionaries also accept larvas).

Why

"Larva" comes from Latin words for "ghost" or "mask" — it originally described something disguising or spectral in appearance, a sense 18th-century naturalists later repurposed for the transformed, immature stage of an insect. Grammatically it's a standard first-declension Latin noun, so English kept the native -a-to-ae plural switch that produces "larvae."

Because "larva" lives almost entirely within biology and entomology, a field where Latin scientific naming remains the norm and where specialists are trained early to use classical plurals correctly, the word has shown very little pressure to regularize toward "larvas" the way more everyday Latin borrowings often do. The transformation from larva to adult, called metamorphosis, varies dramatically across species — some insects undergo a dramatic, near-total restructuring inside a pupal stage, while others develop more gradually through a series of molts without ever forming a true pupa — a biological distinction unrelated to the word's grammar but frequently discussed in the same educational contexts where the plural "larvae" is introduced to students.

Usage note

"Larvae" is essentially universal in scientific, educational, and even general nature writing; "larvas" does appear occasionally in casual conversation, particularly among people without a biology background, but it reads as noticeably informal or even mistaken in any writing that takes the subject seriously.

"Larval," the adjective derived from "larva," is fully regular and used constantly in biology to describe the entire developmental stage generally ("larval development," "larval stage"), distinct from the countable noun's own plural debate, since adjectives don't carry number the way the underlying noun does. Pest-control writing distinguishes carefully between adult insects and their larvae when describing treatment methods, since many pesticides and interventions target one life stage far more effectively than the other, making the singular/plural distinction genuinely practically important in that specific professional context. Aquarium hobbyists sometimes deliberately raise larvae as live food for larger fish, a practical application that relies on understanding the word's correct plural for ordering and labeling supplies correctly.

Common real mistakes

Treating "larvae" as if it were itself singular is a real, if less frequent, mistake among younger students first learning the term — a single immature insect is always "a larva," never "a larvae," a distinction reinforced constantly in science classrooms specifically because the confusion is so common early on. A further point of confusion: the word "pupa" (the intermediate, often immobile stage between larva and adult) has its own separate Latin plural, "pupae," following the identical -a/-ae pattern, but it describes a distinct developmental stage from "larva" entirely, not simply an alternate name for the same thing.

The wider pattern

"Larva/larvae" shares its Latin -a/-ae pattern with "antenna/antennae" and "vertebra/vertebrae," all three concentrated heavily in biological and scientific writing where the classical plural has stayed essentially unshaken by everyday regularization pressure.

Examples

• Mosquito larvae develop in even small amounts of standing water.
• The aquarium tank was full of tiny fish larvae.
• A single larva can grow rapidly once it starts feeding.
• Scientists studied how larvae respond to changes in water temperature.
• Butterfly larvae, better known as caterpillars, eat enormous amounts of leaves.
• The pond's surface was covered with mosquito larvae by midsummer.
• Each larva molts several times before reaching adulthood.
• Researchers collected larvae from three different habitats.
• The beetle's larvae bore directly into the wood of dead trees.
• Fly larvae, or maggots, are commonly used in forensic investigations.
• The classroom raised butterfly larvae to observe metamorphosis firsthand.
• Fish larvae are especially vulnerable during their first few weeks of life.
• The pond's surface teemed with mosquito larvae after the summer rains.
• A parasitic wasp lays its eggs directly inside a host larva.
• Each larva consumed several times its body weight in leaves daily.
• The nature documentary followed a single larva from hatching to adulthood.
• Beekeepers check larvae carefully to gauge the health of the colony.