The bugs most likely to bite you at night are mosquitoes, bed bugs and fleas. Chiggers and ticks picked up outdoors during the day can also leave bites you only notice in bed, spiders bite sleeping people only rarely, and in the southern US, kissing bugs feed at night. Bite marks alone rarely identify the culprit. Finding the bug, or its signs, is the only reliable answer.
This guide helps you narrow it down and decide what to do. It isn’t medical advice: for a bite with worrying symptoms, see the safety section below.
Night biters at a glance #
| Bug | Where bites tend to appear | Other clues |
|---|---|---|
| Mosquitoes | Exposed skin: face, arms, ankles | Buzzing near your ear, open windows or torn screens, standing water nearby |
| Bed bugs | Skin exposed while sleeping, often several bites together | Rusty spots and dark specks on sheets and mattress seams; bites keep appearing indoors |
| Fleas | Often ankles and lower legs | Pets scratching, tiny jumping bugs, black specks that smear red when wet |
| Chiggers | Ankles, behind knees, waistband, armpits | Recent time in tall grass or brush; intense itch 12 to 24 hours later |
| Ticks | Anywhere, often hairline, armpits, groin, waistband | A tick may still be attached |
| Spiders | Usually a single bite | Rare; typically when a spider is trapped against skin |
| Kissing bugs | Often the face or other exposed skin | Southern US; the bite usually doesn’t hurt while they feed |
Mosquitoes #
Mosquitoes are the most common night biters. Many species, including the common house mosquito, are most active from dusk through the night, while others like the Asian tiger mosquito bite mainly in the daytime. The bite is a single raised, itchy bump on uncovered skin.
The CDC’s prevention advice is to use screens on windows and doors, use an EPA-registered repellent (DEET, picaridin, IR3535, oil of lemon eucalyptus, para-menthane-diol or 2-undecanone), and empty, scrub, turn over or cover anything that holds water once a week. A single mosquito indoors can bite several times in one night; a fan blowing across the bed also helps, since mosquitoes are weak fliers.
Bed bugs #
Bed bugs feed on sleeping people, usually on skin that’s uncovered at night. Bites often appear several at a time. But the EPA calls bites a poor indicator of bed bugs, because they look like other bites and rashes, and the University of Kentucky notes that about 30% of people don’t react at all, while others react days later.
So look for evidence instead:
- Rusty or reddish stains on sheets from crushed bugs
- Dark spots about the size of a period that bleed into fabric like a marker
- Tiny pale eggs, shed skins and live bugs in mattress seams, box spring corners and headboard cracks
Bed bugs don’t spread disease, but they’re hard to get rid of alone. See bed bug vs carpet beetle and tiny black bugs in bed for what to check and what to do next.
Fleas #
Flea bites are small, very itchy red bumps, often on the ankles and lower legs. The CDC notes fleas prefer animal hosts and bite people when an animal isn’t available. They may be the problem if you have a cat or dog, a pet recently stayed elsewhere, or you moved into a home where a previous owner had pets.
The CDC’s advice centers on the pet: talk to your veterinarian about flea control, treat pets year-round, vacuum carpets, rugs and upholstery often, and wash bedding, especially pet bedding.
Chiggers #
Chiggers are larval mites so small you’ll almost never see them. You pick them up in tall grass, brush or unmown areas, and the itching starts later, often when you’re in bed. The University of Kentucky says bites typically show up 12 to 24 hours after exposure, around the ankles, knees, armpits and anywhere clothing is tight, and can be inflamed, hard and reddish.
Kentucky suggests over-the-counter anti-itch products such as hydrocortisone or calamine lotion for relief, and for prevention, DEET on skin, permethrin on clothing, and avoiding overgrown areas. Chiggers don’t burrow into skin or stay attached for days, despite the old myth.
Ticks #
A tick bite is often painless, and ticks can stay attached for days. If you find a tick in the evening, remove it right away with fine-tipped tweezers, pulling upward with steady pressure, as the CDC describes. Save it in a sealed bag and see your doctor if you develop a rash or fever within several weeks. Our deer tick vs dog tick guide explains which ticks carry which diseases.
Spiders #
Spiders get blamed for many bites they didn’t cause. Most spiders avoid people, and UC IPM notes that spiders are unlikely to bite unless trapped against the skin, as can happen when you roll over in bed or put on clothing a spider is hiding in. A true spider bite is usually a single spot.
The two that matter medically in the US are the black widow and the brown recluse. See brown recluse vs wolf spider for how to recognize a recluse, and get medical advice for a bite that spreads, darkens, or comes with cramping, fever or feeling unwell.
Kissing bugs #
Kissing bugs (triatomines) are blood-feeding insects about 1/2 to 1 inch long. Texas A&M’s Kissing Bug Community Science Program reports they’ve been documented in 29 US states, mostly in the South, with Texas, New Mexico and Arizona having the most species. They’re mostly active at night, and their bites usually don’t hurt while they feed.
Some carry the parasite that causes Chagas disease. The CDC explains that it spreads mainly through the bugs’ droppings, not the bite itself. If you find a bug you think is a kissing bug, don’t crush it with bare hands; trap it in a container and contact your local health department or a program like Texas A&M’s for identification. Several harmless assassin bugs, like the wheel bug, look similar.
When it isn’t a bug #
Hives, eczema, contact dermatitis and other skin conditions can look very much like bites. If you have new “bites” every morning but can’t find any bug, fleas or bed bug signs after a careful search, it’s worth showing the rash to a doctor or dermatologist.
Treating bites and when to get help #
For most bites, MedlinePlus advises washing with soap and water, applying wrapped ice for 10 minutes on and 10 minutes off, and using an antihistamine or anti-itch cream if needed. Try not to scratch, and watch for signs of infection (spreading redness, warmth, swelling or pus) over the next few days.
Call 911 for trouble breathing or wheezing, swelling of the face, lips or throat, difficulty swallowing, weakness or fainting. For advice on a bite or sting that isn’t an emergency, call Poison Control at 1-800-222-1222, free and confidential in the US. See a doctor for fever, a spreading or target-shaped rash, a wound that grows or darkens, or any bite on someone very young, very old or medically fragile.
Find and identify the culprit #
The best clue is the bug itself. Check sheets and mattress seams, look at your pets, and set sticky traps near the bed if you suspect crawling insects. Once you catch something, a close photo helps you name it.
Insect Identity can check that photo in about a second, offline. It knows the bed bug, cat flea, common house mosquito, Asian tiger mosquito, yellow fever mosquito, deer tick, American dog tick, lone star tick and common house spiders, among its 224 species, and shows a best match with a confidence score and four runners-up. It doesn’t include chiggers, mites or kissing bugs, and it can’t tell you anything from a photo of a bite, only of a bug. Use it to name what you caught, and leave health decisions to a medical professional.
Frequently asked questions #
What is biting me at night but I can’t see anything? #
Common invisible or hard-to-find culprits are chiggers (picked up outdoors earlier), bed bugs hiding in mattress seams, and fleas from pets. Check bedding seams with a flashlight, look for dark specks and rusty stains, and consider whether you were in tall grass recently. If nothing turns up, a skin condition may be the cause.
How do I know if it’s bed bugs or mosquitoes? #
Mosquito bites happen on exposed skin, often come with buzzing, and stop when windows are closed and screened. Bed bug bites keep appearing indoors, often several together, and come with signs on the mattress such as dark spots, rusty stains and shed skins.
Do spiders bite you in your sleep? #
Rarely. Most spiders avoid people, and bites mainly happen when a spider is pressed against skin. Many “spider bites” turn out to be other bites or skin infections, so see a doctor if one is getting worse.
Which night bites need a doctor? #
Get medical care for signs of allergic reaction, spreading redness or pus, fever after a bite, a rash after a tick bite, or a wound that grows or turns dark. When unsure, Poison Control (1-800-222-1222 in the US) can help you decide.