While they’re totally different species, people often lump mites and fleas together because they’re small (sometimes microscopic) bugs. They both live in groups and can infest our homes and pets.

In the case of both mites and fleas, many types don’t bite or cause any harm to people. But there are some varieties with bites that can produce itchy rashes or other skin reactions, allergies, or more serious health complications.

Here’s a description of each type of bug and what you need to know about the health effects of their bites.

Mites are arthropods, not insects, and are close cousins with spiders and ticks. Most types of mites feed on other insects or on dead plant and animal material. (Dust mites, for example, feed mostly on dead skin cells.)But there are a few types that bite or have effects on humans:

• Chiggers

• Scabies

• Rat mites

• Bird mites

• Northern fowl mites

Home mite infestations are fairly rare and tend to be much less of an issue than people assume, says Mike Merchant, PhD, a former professor of entomology at Texas A&M University AgriLife Extension in Dallas. “A lot of the mite stuff on the internet makes it sound like [a mite infestation is] the end of the world, but it’s not,” he says.

Mite bites can cause skin lumps and rashes and, occasionally, more serious reactions, Dr. Merchant says.

Among outdoor mites, the only type that frequently bites people is the chigger. The word “chigger” applies to a particular species of mite that bites during its larval stage of development, and their bite produces an intensely itchy red welt, Merchant explains. “There are not too many other mite problems outdoors,” he adds.

When it comes to indoor mites that bite or cause health issues, Merchant says most come from animal nests. “Some mites will infest the nests of birds and rats and mice, and when they become abundant, they’ll leave that site and sometimes wander into the house and bite people,” he explains. In most cases, the bites of these mites cause an itchy skin rash, which may produce small lumps or pimples.

“The skin might be very itchy or red for a few days, but that will taper off,” Merchant says of mite bites. Ice and anti-itch creams like hydrocortisone can control the swelling and itching. But those symptoms should resolve within a week, he says. (Nearly all species of biting house mites cannot live on human beings, and so they don’t “infest people,” he adds.)

There is one outlier: scabies. These mites infest a person’s skin in order to lay eggs and feed, and they usually only transmit between humans through direct person-to-person contact. Like other mites, scabies tend to cause an itchy, pimply red rash. But unlike other mites, those rashes will continue to appear unless the person gets medical treatment, usually a prescription-only skin cream or lotion designed to kill scabies.Dust mites can cause allergies in some people, but these tend to be of the mild, seasonal allergy variety — stuff like a runny nose, sneezing, and itchy eyes. Over-the-counter and prescription allergy meds can ease the symptoms.

You don’t need a whole-house treatment or fumigation. You just need to remove the animals and animal nests that are bringing mites into your home, Merchant says. “Everybody always wants a spray to solve these types of mite problems, but the real solution is animal-proofing your home and getting rid of any animals nesting there,” he says. Basically, call in a home pest pro.

The exception here, again, is the scabies mite. Along with medical treatment, you can take steps to eliminate the mites from your household. Scabies mites don’t survive very long when they’re not on human skin. Vacuum your home the day you start treatment and decontaminate your bedding, clothing, and towels by washing these items in hot water and drying on high heat. You can also dry-clean or seal these articles in a plastic bag for at least 72 hours.

On the other hand, it’s almost impossible to get rid of all dust mites. But frequent home cleaning and dusting, installing HEPA air filters, and buying bedding that’s washable in hot water and that resists dust buildup can limit allergic reactions.

Fleas are blood-sucking insects that live on mammals — often dogs, cats, or other furry pets. Fleas are brown and wingless. Even though they’re small (usually around 1/8 inch), fleas are big enough to see or even feel with your hand, Merchant says.

While they prefer animals to humans, fleas can migrate from pets onto their owner’s skin. “Usually, fleabites are on the lower legs because the fleas get into the carpet and then jump up as we’re walking past,” Merchant explains.

What does a fleabite look like? Like many other types of insect bites, fleabites produce small red bumps that may be itchy and tend to appear in groups of three or more. Again, ice and hydrocortisone can help relieve symptoms, which tend to be short-lived — a week or less.

Flea treatment for pets is one of the best ways to keep these bugs out of your home, Merchant says. Along with pet treatments, frequent vacuuming and carpet cleaning — and washing your pet’s bed in hot soapy water — is another way to kill off or remove fleas.

If you don’t have pets but have fleas in your home, Merchant says it’s a good bet that you have some other furry animal living in or under your dwelling. “It’s usually something like a possum or feral cat that’s gotten under the house or into a crawl space,” he says. Call a pest control expert, he advises.

Like all biting or stinging insects, mites and fleas can occasionally cause serious allergic reactions, including problems breathing or a swollen limb or throat. Those symptoms warrant a trip to the emergency room.

Also, any skin wound that causes itching or open sores can allow bacteria to enter. This might lead to a secondary infection. Talk to a doctor if you notice swelling, pain, or a mite bite or fleabite that seems to be getting worse after a day or two or if you have a fever or other flu-like symptoms. Those could be signs of a bacterial infection.Finally, both fleas and mites can transmit some potentially serious diseases to humans — namely types of typhus and spotted fever — though these transmissions are very rare. Symptoms include headaches, fever, rashes, and delirium.

• Mites and fleas are small bugs that can invade your home, but not all of them bite or harm humans.

• Fleabites are noticeable by their small red bumps.

• While many types of mites live unnoticed, a few types — like scabies mites — can cause persistent skin issues.

• To minimize both kinds of pests, regularly clean your home, ensure it is animal-proofed, and have your pets evaluated and treated.