Mosquito Identification: Telling It From Look-Alikes

• Vs. crane fly: crane flies are larger than mosquitoes and their wings lack the scales found on mosquito wings.
• Mosquito wings are covered in small scales, unlike crane fly wings.
• Only female mosquitoes bite/feed on blood; males feed on plant juices/sugar sources, not blood.
• Crane flies (often nicknamed "mosquito hawks") are harmless and do not bite, unlike mosquitoes — the belief that they prey on mosquitoes is itself described as a common misconception in the source.

People most often mix mosquitoes up with:

• Flies

Open the other page and compare its list against the marks above; the differences are usually in the antennae, wings or the way the body is divided.

Female mosquitoes bite to obtain blood needed to develop eggs; bites can transmit disease-causing viruses to humans. Seek medical care promptly for severe symptoms or any allergic reaction.

Mosquitoes are treated as a pest/public-health concern because their bites can transmit viruses that cause human disease.

Mosquito larvae occur in stagnant or nearly still water — surface pools, tree holes, or man-made containers; species habitats in California range from below-sea-level deserts to high mountain meadows.

Get as close as your camera will focus, from directly above, in daylight or a bright lamp. Include the whole body with the legs and antennae in frame; a second shot from the side shows wings and body segments. Put a coin or ruler next to it for scale. For a bite or a bug found on skin or bedding, photograph the bug itself, not the mark. The app names the likely group; use the list above to confirm.

To identify a mosquito, look for a long, straw-like proboscis, scales along the wing veins and edges, and long legs on a body about 1/4 to 1/2 inch long (Missouri Department of Conservation).

• Proboscis: a long mouthpart sticking forward from the head, used like a straw (Missouri Department of Conservation).
• Wing scales: one pair of clear wings fringed with hair and scales along the edges and veins. Midges, crane flies and gnats have no scales on the wing veins (Missouri Department of Conservation; Sacramento-Yolo Mosquito & Vector Control District).
• Male or female: males have feathery antennae and feed only on nectar; only females take blood (Missouri Department of Conservation).

Clarke, a mosquito control company, groups the mosquitoes people usually meet into four genera:

• Aedes: often black and white striped legs and body, a pointed abdomen, and biting in the daytime as well as at dawn and dusk; breeds in temporary pools and containers in towns. Linked to dengue, yellow fever, chikungunya and Zika (Clarke). The Wellcome Sanger Institute notes they rest and bite hunched over, like an upside-down V.
• Culex: dark brown to black, rounded abdomen, rests parallel to the surface, bites at dawn and dusk and breeds in ditches and ponds; linked to West Nile virus (Clarke).
• Anopheles: spotted wings, long palps beside the proboscis so the head seems to have three tubes, and a steep resting angle with head, thorax and abdomen in one line; they are never stark black and white striped (Wellcome Sanger Institute; Clarke). Only females of this genus transmit malaria to people.
• Culiseta: larger, with a long drooping proboscis, active at night in damp, shaded woods; linked to eastern equine encephalitis (Clarke).

The resting posture is the easiest field check: a straight body held at an angle to the surface suggests Anopheles; a hunched body suggests Aedes, and a body held parallel to the surface suggests Culex (Wellcome Sanger Institute; Clarke).

The Sacramento-Yolo Mosquito & Vector Control District lists these look-alikes:

• Chironomid midges: about 1/2 inch, light green to brown, with bushy antennae; they do not bite.
• Crane flies: a body up to an inch long and long dangling legs, a V-shaped groove on the thorax, non-piercing mouthparts and no scales on the wing veins; they do not bite. See flies.
• Gnats: dark, delicate insects with slender legs; they do not bite people.
• Moth flies: hairy, brownish, gold or grey, with moth-like wings, found around bathroom and kitchen drains; they do not bite.
• Black flies: small, humpbacked and greyish-black; they do bite, painfully, in daylight.
• Sand flies: 2 to 5 mm; their bites leave large, red, itchy bumps.

The Missouri Department of Conservation adds mayflies, stoneflies, caddisflies, damselflies and green lacewings to the list of insects people confuse with mosquitoes.

Mosquito larvae, called wrigglers, have a large head and thorax and a narrow, worm-like abdomen, and hang just below the water surface breathing through a tube. The pupae, called tumblers, are comma-shaped and also stay just under the surface. In ideal conditions the whole cycle from egg to adult can take as little as 10 days (Missouri Department of Conservation). That is why the CDC advises emptying or scrubbing water-holding containers once a week.

The CDC and EPA recommend EPA-registered repellents with one of six active ingredients: DEET, picaridin (called icaridin outside the US), IR3535, oil of lemon eucalyptus (OLE), para-menthane-diol (PMD) or 2-undecanone. OLE and 2-undecanone are plant-derived, so if you want a plant-based option, those are the ones with registered evidence. The CDC says the effectiveness of repellents that are not EPA-registered is unknown, and warns not to use products containing OLE or PMD on children under 3 years old. Long sleeves, permethrin-treated clothing and window screens also cut bites (CDC). For what bites look like, see mosquito bites.

Photograph a resting mosquito from the side so the resting angle, the legs and the palps beside the proboscis all show; a second shot from above shows wing spots and body stripes. Photograph it and InsectLens identifies it.