What insect caused that swollen red welt? Is that rash of itchy dots on your ankle actually bug bites? Insect bites can be hard to decipher — even for experts. But identifying common insect bites with pictures makes it a little easier.

“Human bodies react so differently that it’s not (always) possible to look at the results of a bite and determine what caused it,” he says.

While some people might break out in itchy or painful welts after a get mosquito or ant bite, others will barely notice. And, for some, an insect bite or sting can mean a severe allergic reaction — and even a trip to the emergency department.

“We look at patterns and where on the body they were bitten,” she explains. For instance, clusters of small bites on the ankles could signal chiggers while larger welts on exposed arms and legs might be due to mosquitoes. Experts will also take into account what you were doing when you got the bite, other symptoms you have and whether or not you got a look at the insect that was responsible.

Should you see a doctor for a bug bite?

Thankfully, while bug bites can be annoying, most are not seriously harmful for humans, Kassouf says.

While the insect bites heal, you can likely manage the symptoms at home with remedies like oral antihistamines or a cool compress, Kassouf says. Or you can try topical treatments, like hydrocortisone or topical antihistamines.

But if you develop certain serious signs, you should check in with your doctor or get medical attention quickly. That includes symptoms of an allergic reaction, such as swelling in the mouth, trouble breathing or a widespread rash, Kassouf says. Additionally, if you develop signs of a larger infection, like pus or a fever, you should see a doctor.

Here are some of the mot common bug, insect and spider bites you might be dealing with — and insect bite pictures to help you figure out which bug is responsible.

Tick bites

What they look like:

Most people don’t notice when a tick bite them because ticks are so small and hard to see. Additionally, “ticks have factors in their saliva that prevent pain, clotting and an immune reaction,” Frye told TODAY.com previously. So you may never see or even feel any evidence of the tick bite, he says.

After a tick bite, some people do develop a small, red, itchy bump, the Mayo Clinic says. The bump may resemble a mosquito bite at this stage.

If the tick was carrying certain tick-borne illnesses, such as Lyme disease or Rocky Mountain spotted fever, a tick bite may lead to distinctive rashes that appear in the weeks following the bite. However, the rash may not appear on the part of the body where you were bitten, which makes it more challenging to interpret.

Other symptoms:

In the weeks following a tick bite, you may start to feel flu-like symptoms such as a fever, headache, chills, fatigue, and muscle and joint pain. Some people also develop a distinctive “bullseye” rash, as described above.

If you have symptoms like these, you should see a doctor to get evaluated. This is especially important if you know you were bitten by a tick or you recently spent time outdoors in tick-heavy areas because your doctor may be able to prescribe prophylactic medications to help manage a tick-borne illness.

Chigger bites

What they look like:

Chiggers, a type of small mite, typically leave clusters of bites. If you have chigger bites, they’ll be small, red and likely quite itchy. Chigger bites may also look like tiny blisters or pimples, TODAY.com explained previously. They can also look like hives, and you may also develop a rash around the bites.

Generally, chiggers tend to bite along the clothing line. For instance, people often notice chigger bites right where skin peeks out just above the socks or along the waistband of leggings. The mites can also bite in between the folds of skin where it’s warmer.

Other symptoms:

Chigger bites start out painless, but they will become itchy a few hours later. In the first two days, that itchiness is at its most severe. It then usually subsides over the next week.

If you scratch at the bites, you can develop a secondary skin infection, which can cause swelling and pus along with the itchy bites.

Bedbug bites

What they look like:

Bedbugs, which are parasites that feed on human blood, tend to bite during periods of time when people are immobile. That means they’re most likely to bite overnight while we’re asleep, when we’re sitting still watching a movie on the couch or taking a long train ride.

What makes them hard to identify is that not everyone develops obvious signs of a bedbug bite. For some people, the bites may go unnoticed because they’re small and not itchy. But other people can develop overwhelmingly itchy, raised red welts that look like mosquito bites or hives after being bitten by a bedbug.

Bedbugs are able to bite any area of skin that isn’t tightly covered by clothing. Most often, they bite on the arms, legs and back — whatever is easiest for them to reach.

Bedbugs may bite in a line, a sign that experts sometimes call a “breakfast, lunch and dinner” pattern, Dr. Benjamin N. Ungar, director of the Alopecia Center of Excellence and director of the Rosacea and Seborrheic Dermatitis Clinic at Mount Sinai, told TODAY.com previously.

Other symptoms:

In general, bedbug bites can feel similar to other bug bites. They may be itchy and inflamed for a few days before the itchiness subsides and the skin heals.

But some bedbug bites can be serious. In those cases, people can develop such a strong allergic reaction to bedbug bites that they’re in danger of developing anaphylaxis, which can be life-threatening.

Signs of a more severe bedbug bite reaction include itchiness in areas that weren’t bitten, swelling in the lips or tongue and trouble breathing. If you have bites along with any of these other symptoms, you should seek medical attention immediately.

Spider bites

There are only a few species of spiders in the U.S. that can bite humans.

“The truth is that most spiders are too small to bite us, including those adorable jumping spiders,” Jody Gangloff-Kaufmann, Ph.D., an urban entomologist and coordinator with the New York State Integrated Pest Management community program at Cornell University, told TODAY.com previously.

But there are a few species that, when they bite, can cause serious symptoms.

Brown recluse spider bites

What they look like:

At first, a brown recluse spider bite may look like a bug bite or bee sting. It can be a small, raised red or purplish bump. You may see a tiny pinprick or two fang marks at the area of the bite.

Over the course of a few hours, the skin may start blistering and the red or purplish color can radiate out from the bite site. From there, the venom can cause skin cell death (necrosis), Dr. Melissa Levoska, an assistant professor of dermatology at the Icahn School of Medicine at Mount Sinai, told TODAY.com previously.

Brown recluse bites may cause an area of dead skin that’s called an eschar, which typically sloughs off and leaves an ulcer behind.

Other symptoms: