Plural of “mosquito”

The plural of mosquito is mosquitoes (some dictionaries also accept mosquitos).

Why

"Mosquito" comes from Spanish and Portuguese, a diminutive of "mosca," fly, literally meaning "little fly." English borrowed the word in the 16th century as explorers and colonists encountered the insect across the Americas, and it settled into the traditional -oes plural pattern common among earlier consonant-plus-o borrowings.

"Mosquitoes" remains the more traditional and more common spelling in careful writing, including scientific and public-health contexts, but "mosquitos" appears often enough in general use — advertising, casual writing, product names for repellents — that dictionaries list it as an accepted, if less formal, variant. English absorbed the word relatively unchanged from Spanish, which is itself notable since most Spanish loanwords from this period were adapted more heavily to English spelling conventions; "mosquito" instead kept its Spanish spelling almost entirely intact.

Usage note

"Mosquitoes" is the safer default in medical, scientific, and formal writing ("mosquitoes transmit several serious diseases"). "Mosquitos" is common in casual and commercial writing and won't strike most readers as wrong, but it's worth staying consistent within a single document. Public-health agencies like the CDC and WHO consistently use "mosquitoes" in official materials, which has helped anchor that spelling as the expected form in any writing about disease transmission or vector control.

The word's diminutive origin, literally "little fly" in Spanish and Portuguese, is a small but genuine irony given how disproportionately dangerous the insect has turned out to be to human health worldwide; entomologists sometimes note this mismatch between the word's modest literal meaning and the outsized threat the insect actually poses as the deadliest animal to humans by disease transmission. English picked up "mosquito" specifically through contact with Spanish- and Portuguese-speaking explorers and colonizers in the Americas and the Caribbean in the 1500s, rather than through direct Latin or Greek scientific naming the way many other insect names entered the language, which explains why its plural never settled into a classical pattern at all. Entomological writing distinguishes over three thousand known mosquito species worldwide, and formal taxonomic writing about specific species ("Aedes mosquitoes," "Anopheles mosquitoes") still pluralizes the common English word normally even while pairing it with an italicized Latin genus name that itself follows separate scientific naming conventions.

Common real mistakes

The real risk with this word isn't the plural but confusing which insects actually spread disease; grammatically, the only genuine slip is switching spellings mid-document rather than choosing one form and sticking with it. Some writers also mistakenly assume "mosquito" must take a Latin-style plural given its scientific and medical associations, producing an invented form like "mosquiti" — the word is a Spanish/Portuguese diminutive, not Latin, so no such classical plural exists or has ever been standard.

The wider pattern

"Mosquito" belongs with "volcano" and "tornado" in the subgroup of -o nouns where the older -oes plural remains dominant in formal writing while a newer, regularized -os spelling has become genuinely accepted rather than simply tolerated as a common error.

Examples

• Swarms of mosquitoes descended at dusk near the marsh.
• The spray kept mosquitoes away for most of the evening.
• Public health officials warned about disease-carrying mosquitoes.
• Standing water attracts breeding mosquitoes within days.
• Researchers are studying genetically modified mosquitoes to reduce malaria.
• The campsite was overrun with mosquitos by nightfall.
• Several species of mosquitoes are native to the region.
• Netting kept the mosquitoes out of the tent.
• The wetlands provide ideal breeding grounds for mosquitoes.
• Bites from local mosquitoes left the hikers covered in welts.
• Local authorities sprayed the park to reduce the mosquito population.
• The lab tested whether the new repellent actually deterred mosquitoes.
• The wetlands survey counted several mosquito species new to the area.
• Residents complained about mosquitoes swarming near the retention pond.