Photos: Trombocyte / Fotolia
Most bug bites can be told apart by three clues: the pattern (a single bump, a cluster or a line), where on the body they appear, and how they feel (instant pain, slow itch or nothing at first). Mosquito bites are puffy and itchy, flea bites cluster around the ankles, bedbug bites show up on skin exposed during sleep, and stings from bees, wasps and fire ants hurt immediately. A tick is usually still attached when you find it.
Identifying the culprit matters because a few of these creatures carry disease and some people react strongly to venom. This guide covers twelve of the most common biting and stinging pests in North America and Europe, what their marks typically look like, and when a bite needs a doctor's attention. Photos are for general recognition only; bites look different from person to person, so if you are unsure or worried, talk to a doctor.
Ticks and mosquitoes: the disease carriers
1. Ticks
YouTube / CropWatch
Ticks are arachnids, relatives of spiders, that wait on grass and shrubs and climb onto passing animals and people. Their bite is usually painless, so many people only notice a tick when they find a small dark bump firmly attached to the skin, often in warm areas such as the groin, armpits, behind the knees or along the hairline.
After a tick is removed, a small red spot is normal. A red patch that keeps expanding over days, sometimes with a clearer centre that gives a bull's-eye look, can be a sign of Lyme disease. Ticks also spread other infections, including Rocky Mountain spotted fever in the Americas. The US Centers for Disease Control and Prevention (CDC) advises seeing a doctor if you develop a rash or fever in the days or weeks after a tick bite, and telling them when and where the bite happened.
How to remove a tick
The CDC's advice is to act quickly rather than wait for an appointment:
- Grasp the tick as close to the skin as possible with clean, fine-tipped tweezers.
- Pull straight upward with steady, even pressure. Do not twist or jerk.
- If the mouthparts break off and do not come out easily, leave them; the skin usually pushes them out as it heals.
- Clean the bite and your hands with soap and water, rubbing alcohol or hand sanitiser, and check the rest of your body for other ticks.
- Do not use petroleum jelly, nail polish or heat to make the tick let go. These can make it release more fluid into the skin.
2. Mosquitoes
TreeHugger / Trombocyte
Only female mosquitoes bite, because they need protein from blood to produce eggs. The result is the familiar puffy, pale or pink bump that appears within minutes and turns into a firm, itchy red spot over the next day. Bites tend to appear on exposed skin and can be scattered randomly.
The itch comes from your immune system reacting to proteins in the mosquito's saliva. Scratching breaks the skin and can lead to infection, so it is worth resisting. In many regions mosquitoes can transmit diseases such as West Nile virus, dengue or malaria, so fever after travel to a risk area is a reason to see a doctor.
Stinging insects: wasps, bees, hornets and fire ants
These insects do not bite to feed. They sting to defend themselves or their nest, injecting venom that causes immediate, sharp pain followed by redness and swelling.
3. Wasps
Adams / Fotolia
Wasps, including the yellowjackets pictured, can sting repeatedly because their stinger is smooth. A sting usually leaves a red, swollen welt with a small puncture mark at the centre; the swelling can be larger than a mosquito bite and may itch for a day or two afterwards. Wasps become more defensive in late summer, when colonies are large and food is scarce.
4. Bees
Vox / Hunker
Honeybees have a barbed stinger that lodges in human skin. When the bee pulls away, the stinger, venom sac and part of its abdomen are left behind, and the bee dies. Bumblebees, like the one in the photo, can sting more than once but rarely do.
A stinger left in the skin is the easiest sign of a honeybee sting. Removing it quickly matters more than the method, because the attached venom sac can keep pumping venom for a short time.
5. Hornets
pestre.ro / Sussex Scrapbook
Hornets are simply large wasps, and their stings are not fundamentally different, though they often hurt more and can cause marked swelling, as on the hand shown here. The insect in the photo looks like a paper wasp, which is easy to confuse with a hornet.
Swelling around the sting site, even if large, is usually a local reaction. Symptoms elsewhere in the body are a different matter; see the warning signs in the treatment section below.
6. Fire ants
NPR / Medical News Today
Most ants are harmless, but red imported fire ants, an invasive species in the southern United States and other warm regions, attack in numbers when their mound is disturbed. Each ant bites to grip the skin and then stings, often several times. The sting burns, which is how they got their name, and it typically forms a small white pustule.
Leave the pustules intact, as breaking them can lead to infection. A small percentage of people are allergic to fire ant venom and can have severe reactions.
Fleas, lice and bedbugs: small biters that cluster
7. Fleas
Den Herder Veterinary Hospital / Pest Removal Guide
Flea bites usually appear as small, very itchy red bumps in groups, most often around the ankles and lower legs, because fleas jump up from carpets, bedding or pets. A small red halo around each bump is common.
If you have pets and keep finding bites at ankle height, check your animals and talk to a vet about flea control, since treating the pet and the home together is what ends the problem.
8. Lice
Reader's Digest / Healthline
Head lice live on the scalp and lay eggs, called nits, firmly attached to hair shafts near the root. The main symptom is itching on the scalp, behind the ears and on the back of the neck, where scratching can leave small red spots, as in the photo.
Head lice spread mainly through head-to-head contact and are common among schoolchildren. They are a nuisance but not a sign of poor hygiene and do not spread disease. Body lice, which live in clothing, are a separate species associated with crowded conditions.
9. Bedbugs
McCall Service / OnHealth
Bedbugs hide in mattress seams, bed frames and furniture and feed at night. Their bites are often found in a line or small cluster on skin exposed during sleep, such as the arms, shoulders and neck, and are easy to mistake for mosquito bites. Some people do not react at all.
Better clues than the bites are signs in the bed itself: tiny dark spots of droppings, shed skins or small blood stains on sheets. Bedbugs are not known to spread disease, but infestations are stressful and usually need professional treatment. Pus is not a typical feature; it suggests infection from scratching and is worth showing to a doctor.
Biting flies: horse-flies and deer flies
10. Horse-flies
Female horse-flies slice the skin with blade-like mouthparts and lap up the blood, so the bite is immediately painful. It often leaves a raised, red and swollen area, sometimes with a small wound at the centre, and can itch for days.
Keep the bite clean to prevent infection. Increasing redness, warmth, pus or fever in the following days are reasons to have it checked.
11. Deer flies
Wikipedia / HealthTap
Deer flies are smaller relatives of horse-flies, often with patterned wings, and they tend to circle the head and bite the neck and scalp. Their bites are painful and leave a red bump.
In parts of the United States deer flies can transmit tularemia, a bacterial infection also called rabbit fever or deer fly fever. Its most common form causes a skin ulcer at the bite site with fever and swollen lymph nodes. It is treatable with antibiotics, so see a doctor if those symptoms follow a fly bite.
Spiders: the brown recluse
12. Brown recluse spider
EarthSky / philipcaruso-story
Spiders are not insects, but they are often blamed for mysterious bites. The brown recluse lives in the south-central United States, roughly from Texas and Louisiana north to Missouri, Kansas, southern Illinois and Ohio, and east to Tennessee and Kentucky. It hides in dry, undisturbed places such as closets, woodpiles and stored boxes and bites only when pressed against the skin, for example inside a shoe or clothing.
The bite is often barely felt at first. Pain and redness can develop over several hours, sometimes with a pale or purple centre ringed by red. Most bites heal without lasting harm, but a minority cause an open sore that heals slowly, and rarely fever, chills or more serious illness, especially in children. Anyone with a worsening wound, blistering or fever should see a doctor.
Many wounds blamed on recluse spiders are actually something else, most often skin infections such as MRSA, particularly in places where the spider does not live. That is another reason to get a spreading sore examined rather than assume it is a spider bite.
Basic care and when to get help
Most bites and stings settle on their own within a few days. Keeping the area clean, using a cold compress and avoiding scratching help. For anything beyond that, including medicines for itch, swelling or pain, ask a pharmacist or doctor what is suitable for you.
Call emergency services immediately if, after any sting or bite, someone has difficulty breathing, wheezing, swelling of the face, lips, tongue or throat, dizziness or fainting, or hives spreading over the body. These are signs of anaphylaxis, a severe allergic reaction. People who know they are allergic to stings should talk to their doctor about an emergency plan.
See a doctor soon if:
- a bite becomes more painful, red, hot or swollen after a day or two, or oozes pus;
- you develop a fever, a spreading rash or a bull's-eye pattern after a tick bite;
- an open sore or ulcer forms;
- you were stung many times, or stung in the mouth or throat.
Myths about bites and stings
- “A bull's-eye rash always means a spider bite.” A spreading ring after a tick bite is a classic sign of Lyme disease. Treat it as a reason to see a doctor, not a spider mystery.
- “Burn a tick off or smother it with petroleum jelly.” The CDC advises against both. Tweezers and steady pressure are the safest method.
- “Only dirty homes get bedbugs or lice.” Both spread through contact and travel, not lack of cleanliness.
- “Every unexplained sore is a spider bite.” Doctors often find infections instead, which need different treatment.
Knowing the pattern, place and feel of a bite will usually tell you what you are dealing with. When it does not, or when symptoms worry you, a quick check with a doctor is always the safest choice.
Sources: CDC: What to do after a tick bite; Wikipedia: Brown recluse spider; Wikipedia: Tularemia; Wikipedia: Red imported fire ant; original picture list via Shared and Newsner. Photo credits as shown under each image.
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