Quick answer
A mosquito is a small, long-legged fly whose females bite people and animals for the blood they need to make eggs, and whose young grow only in standing water, from a pond to a bottle cap.
More than 50 species live in California alone. A few carry viruses such as West Nile, the leading mosquito-borne disease in the contiguous U.S.
Quick facts
The key facts about Mosquito, with sources:
Key takeaways
- Only female mosquitoes bite, because they need blood to make eggs.
- Every mosquito starts life in standing water, so emptying containers weekly is the most effective home step.
- Container mosquitoes like the Asian tiger mosquito breed in tiny amounts of water and stay close to home.
- West Nile virus is the leading mosquito-borne disease in the contiguous U.S., peaking late summer.
- Yard sprays give only short relief; repellents, screens and water removal do the steady work.
What a mosquito is
A mosquito is a true fly with one pair of wings, long legs and a long mouthpart for piercing skin. Males feed on plant sugars. Females feed on sugar too, but need a blood meal to produce eggs 2.
Three groups matter most to people in the U.S. Culex mosquitoes are the main carriers of West Nile virus. Aedes mosquitoes include the invasive yellow fever mosquito and Asian tiger mosquito. Anopheles mosquitoes can carry malaria, which was eliminated as a local disease in California by the 1940s 1.
Mosquitoes pick up a virus by biting an infected animal. West Nile spreads mainly when mosquitoes feed on infected birds and then bite people 3.
Not every big “mosquito” bites
Large, long-legged crane flies are often mistaken for giant mosquitoes. Only true mosquitoes have the piercing mouthpart, and only the females bite.
How the mosquito life cycle works
Mosquitoes pass through four stages, and every one depends on water or happens right beside it.
- Egg. Some species lay eggs on the water. Aedes females stick eggs to container walls just above the waterline 2.
- Larva. When water covers them, eggs hatch into larvae, or “wigglers,” that feed in the water through four stages 21.
- Pupa. Pupae live in water but do not eat. Adults emerge in 1 to 2 days 1.
- Adult. Females mate, seek blood and then look for water to lay eggs, starting again 2.
- EggOn water or on a container wall
- LarvaFour stages, feeding in water
- PupaDoes not feed; 1–2 days
- Adult femaleTakes blood, lays eggs
- Back to step 1
Breaking the cycle at the water stage, before adults emerge, is the cheapest and most effective control. Source: [1] [2]
In summer the full cycle can take a week or less 1. That is why CDC asks people to empty water-holding items once a week 4.
Mosquito groups that matter in U.S. homes
| Group | Breeds in | Bites | Disease concern |
|---|---|---|---|
| Culex (house mosquitoes) | Standing water: catch basins, storm drains, ponds, neglected pools 1 | Mostly dusk and night | West Nile, St. Louis encephalitis 1 |
| Aedes aegypti (yellow fever mosquito) | Small containers near homes 2 | Prefers people; indoors and outdoors 2 | Zika, dengue, chikungunya, yellow fever 1 |
| Aedes albopictus (Asian tiger mosquito) | Containers, tree holes 21 | People and animals, outdoors 2 | Same viruses as above 1 |
| Anopheles | Clean standing water | Night | Malaria, rarely reintroduced by travelers 1 |
Worked example: a backyard water audit
This is an example audit of a typical yard, using breeding sites named by UC IPM and CDC. It shows where mosquitoes hide, not a forecast for any yard.
| Item found | Risk | Fix |
|---|---|---|
| Flowerpot saucers with water | Aedes breed in very small amounts of water 1 | Empty and scrub weekly or remove 4 |
| Clogged gutter | Standing water out of sight 1 | Clean gutters at least yearly 1 |
| Birdbath | A full cycle fits in a week in summer 1 | Empty and refill weekly 5 |
| Old tire behind the shed | Classic breeding site 5 | Drill drainage holes or discard |
| Uncovered rain barrel | Large, steady breeding source 1 | Seal or screen it 1 |
| Kids’ toys and buckets | Hold rainwater 4 | Turn over or store indoors |
Aedes fly only a few blocks in their lives, so most of the ones biting you were born close by 2. Neighbors who do the same audit multiply the effect.
Where you will see mosquitoes, and the word on paper
- Shady yard corners, under decks and in dense plants near water.
- Indoors, if screens are torn; Aedes aegypti will live and bite inside 2.
- Wigglers in water: small larvae flicking in buckets or birdbaths 2.
- Public notices from a county mosquito or vector control district about spraying or virus activity 1.
- On a quote: a mosquito control program lists visit frequency, barrier spray areas, larvicide use and whether standing water is inspected.
What works best
Removing standing water works best. UC IPM says the most effective methods target the larval stage, starting with draining or filling anything that holds water 1. The EPA agrees that controlling eggs and larvae is generally the most effective and least costly approach 5.
For water you cannot drain, larvicides target young mosquitoes. UC IPM describes Bti as a highly selective bacterial larvicide that does not affect people, animals or plants, though it also kills some related fly larvae and does not work on pupae 1.
Screens, sealed gaps and EPA-registered repellents protect people while larvae are being controlled 54.
Limits of mosquito control
- Some adults can fly several miles, so your yard alone may not stop biting 1.
- Outdoor sprays and foggers give only temporary drops in adults 1.
- Larval control is rarely 100% effective, especially for Aedes in scattered containers 5.
- Many invasive Aedes populations resist common insecticides 1.
- Bug zappers are counterproductive, killing insects that eat mosquitoes 1.
- Wristbands, ultrasonic devices and vitamin B1 do not work 1.
What drives the cost of mosquito control
We do not quote prices. A yard program’s cost depends on lot size, how many visits run through the season, whether larvicide and standing-water checks are included and whether ticks are bundled in.
The cheapest control is free: a weekly water audit. Paid barrier sprays add relief but need repeating, since their effect on adults is temporary 1. Use our mosquito cost estimator to see how visits and yard size combine.
How integrated mosquito management works
EPA names four core tactics: remove habitat, use barriers, control larvae and control adults 5. Good programs start with a survey so they know where to aim.
- Survey. Count and identify mosquitoes and find breeding sites.
- Remove habitat. Drain or fill standing water; keep pools treated and circulating 5.
- Block entry. Intact screens and sealed gaps 5.
- Control larvae in water that cannot be removed, with EPA-registered larvicides 5.
- Control adults when disease is present or other steps fail, using registered adulticides 5.
This is integrated pest management applied to mosquitoes.
Weekly mosquito upkeep
- Once a week, empty, scrub, turn over, cover or discard anything that holds water, indoors and out 4.
- Change water in birdbaths and pet dishes weekly 1.
- Avoid overwatering lawns and gardens 1.
- Repair holes in window and door screens 4.
- Check the season locally with our pest season calendar.
- Saucers and buckets emptied
- Birdbath refilled
- Gutters flowing
- Rain barrel screened
- Screens intact
Health risks and when to see a doctor
CDC calls West Nile virus the leading cause of mosquito-borne disease in the contiguous U.S. Most infected people have no symptoms, but each year more than 1,300 people develop severe illness and more than 130 die. Season runs typically June through October, with diagnoses peaking late August to early September 3.
Invasive Aedes mosquitoes can carry Zika, dengue, chikungunya and yellow fever viruses 1. See a doctor for fever, headache, body aches or rash after mosquito bites, especially after travel.
Repellent and spray safety
Use only EPA-registered repellents and follow the label. Do not use OLE or PMD on children under 3, and do not put repellent on a child’s hands, eyes or mouth 4. Permethrin is for clothing, never skin. For a swallowed product, call Poison Help at 1-800-222-1222.
Who regulates mosquito control
The U.S. EPA registers every larvicide, adulticide and skin repellent sold in the U.S. 5. CDC advises looking for an EPA registration number on repellent labels and says the effectiveness of unregistered repellents, including some natural ones, is unknown 4.
Community spraying is usually run by local mosquito or vector control districts. California alone has more than 60 1. Private companies applying products in yards need a state license; see our licensing guide and pesticide safety guide. UC IPM notes that releasing mosquitofish into natural waters is illegal in California 1.
Mosquito vs other flying pests
| Pest | Bites? | Breeds in | Main control |
|---|---|---|---|
| Mosquito | Females bite 2 | Standing water 1 | Remove water, larvicide, repellents |
| House fly | No | Garbage, manure, rotting matter | Sanitation and screens |
| Fruit fly | No | Ripe fruit and drains | Remove fermenting food |
| Tick (not a fly) | Yes, attaches | Grass and leaf litter | Yard habitat changes, repellents |
Mosquito myths
- Myth Bug zappers control mosquitoes.
- Reality UC IPM says they are counterproductive 1.
- Myth Citronella plants keep them away.
- Reality UC IPM lists aromatic plants among ineffective methods 1.
- Myth A spray service ends the problem.
- Reality Outdoor sprays give only temporary reductions in adults 1.
- Myth They need a pond to breed.
- Reality Aedes breed in water as small as a bottle cap 1.
- Myth Natural repellents are just as good.
- Reality CDC says effectiveness of non-EPA-registered repellents is unknown 4.
How region changes mosquito risk
Mosquito risk follows climate and local agencies. CDC says Aedes eggs can survive a winter in the southern U.S. 2.
In California, Aedes aegypti and Aedes albopictus arrived in 2011 and 2013 and have spread across Southern California, the Central Valley and the Bay Area 1.
More than 60 California mosquito and vector control districts handle local surveillance, so call your county agency about local virus activity 1.
- 1,300+People with severe illness each yearCDC
- 130+Deaths each yearCDC
- June–OctoberTypical season; peak late August–early SeptemberCDC
Source: [3]
When it matters to you, and what to do next
Start with the weekly water audit and repellent. If you still get bitten heavily after two to three weeks, check neighbors’ yards and storm drains, and call your county vector control agency. If you want added relief for events or a shady yard, compare licensed companies that include a standing-water inspection along with any spraying.
See how to choose a pest control company for the questions to ask.
Quick decision guide
For some bites, run a weekly water audit and use repellent. If heavy biting lasts past 3 weeks, contact the county vector agency, then a licensed program. If you get a fever after bites, see a doctor.
Questions about Mosquito
Why do mosquitoes bite?
Only female mosquitoes bite, because they need protein from blood to make eggs. Males feed only on plant sugars. After a blood meal, a female looks for water to lay her eggs. Mosquitoes find people by sensing breath, body heat and skin odors, which is why some people seem to get bitten more than others.
How long do mosquitoes live?
Adult mosquito lifespans vary by species and weather, and our sources do not give a single figure. What matters more is how fast they breed: in summer, UC IPM says the full cycle from egg to adult can take a week or less. Removing standing water every week stops new adults from emerging.
What attracts mosquitoes to my yard?
Standing water is the main draw, because it is where mosquitoes breed. Shady, humid spots and dense plants give adults a place to rest. Common breeding spots include flowerpot saucers, clogged gutters, birdbaths, tires, buckets, toys and uncovered rain barrels. Aedes mosquitoes can breed in water as small as a bottle cap.
Do mosquito yard sprays work?
Yard sprays reduce adult mosquitoes for a short time. UC IPM says outdoor sprays and foggers give only temporary reductions, and EPA calls controlling eggs and larvae generally the most effective approach. Sprays work best as part of a plan that removes water and treats breeding sites that cannot be drained.
Which mosquito repellent is best?
CDC recommends EPA-registered repellents with DEET, picaridin, IR3535, oil of lemon eucalyptus, PMD or 2-undecanone. UC IPM notes DEET is the most effective choice for long exposure where mosquitoes are heavy. Follow the label, apply sunscreen first and repellent second, and do not use OLE or PMD on children under 3.
Can mosquitoes breed in a pool?
A well-kept pool is not usually a problem, because chlorinated, circulating water does not suit larvae. Neglected or green pools can become major breeding sites. EPA advises keeping pools treated and circulating, and UC IPM lists pools among breeding sites. Pool covers that collect rainwater can breed mosquitoes too.
What diseases do mosquitoes spread in the U.S.?
West Nile virus is the most common, and CDC calls it the leading mosquito-borne disease in the contiguous U.S. Others include St. Louis encephalitis and, mostly through travel, dengue, Zika and chikungunya. Invasive Aedes mosquitoes can carry those travel-linked viruses. See a doctor for fever or rash after bites.
What are mosquito larvae?
Mosquito larvae are the young stage that lives in water, often called wigglers because of how they move. They feed in the water through four stages before becoming pupae. Seeing them in a bucket or birdbath means adults will emerge within days, so dump the water onto dry ground right away.
Do bug zappers and citronella work?
Bug zappers do not help and can make things worse. UC IPM says zappers are counterproductive because they kill insects that prey on mosquitoes. UC IPM also lists aromatic plants, such as citronella, and wristbands as ineffective. EPA-registered repellents and water removal work better.
Sources
- UC Statewide IPM Program, Pest Notes: Mosquitoes (Publication 7451), retrieved .
- U.S. CDC, Life Cycle of Aedes Mosquitoes, retrieved .
- U.S. CDC, About West Nile, retrieved .
- U.S. CDC, Preventing Mosquito Bites, retrieved .
- U.S. EPA, Success in Mosquito Control: An Integrated Approach, retrieved .
Expert review
Written by the HyrePest Research team. Not yet reviewed by an outside expert. We say so rather than imply a review that has not happened; see our editorial policy.
How the numbers were checked: Biology, breeding sites, home steps and California details follow UC IPM Pest Notes 7451; Aedes life cycle and prevention steps follow CDC; integrated management tactics follow EPA; disease figures are from CDC’s West Nile page.
Suggest a correction. We fix errors and say what changed.