Unknown & Mysterious Bug Bites

-- What's biting me ??? --

Summary:

A number of insects and mites can bite and leave a red, swollen, itchy bite mark. There are also many other causes of skin irritation that can be mistaken for bug bites (see below). In many cases, therefore, what appears to be a bug bite may in fact be caused by something else. Below you'll find a list of insects and mites that do bite as well as some things that can be mistaken for bug bites.

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Jack DeAngelis, ext. entomologist (ret.) revised: 11/2018

What if you have bug bites but can't find a bug?

I am frequently asked to diagnosis the cause of bug bites that seem to appear for no obvious reason. There is no insect or mite to identify and the person has either a vague description of what may have bitten them or, ironically, an extremely detailed description.

Most people who contact me believe there are many insects and mites that bite us. In reality there are very few that actually bite people. Take a look at the list of insects and mites below that actually do bite people. If you can not clearly identify one of these as the cause of your bites then you should consider some of the other possibilities. In the descriptions below notice that the bites are all very similar (red, itchy bumps) making any diagnosis from the bite alone nearly impossible.

bug bites
"Bug bites" on wrist and arm.

Bed bugs

Bed bugs cause large, red, splotchy, itchy, mosquito-like bites. Bedding and furniture can be infested and bites generally occur at night. Bed bug infestations are relatively easy to detect but can be difficult to control, see this article for details.

bed bug
bed bug; all stages look similar

Mites

There is a small number of mites that bite people resulting in itchy lesions. A very few also pose some health risk by transmitting disease (ticks) or developing persistent conditions (scabies). These articles should help you identify and treat the mites that affect people.

    bird/nest/rodent mites - mites that originate in the nests of birds or rodents. May invade homes when nests are disturbed.

    chigger mites - tiny biting mites most often encountered outdoors, do not invade or become established in homes.

    pyemotes mites - like chigger mites, pyemotes mites are usually encountered outdoors under very specific conditions.

    scabies mites these tiny mites burrow into skin causing intense itching.

    ticks (yes, ticks are mites) - small to large mites that firmly attach to the host animal (including people) and can sometimes transmit disease.

bird mite
bird mite & human hair (for scale)

Flies

    biting midges - tiny biting flies (midges, gnats) that affect people and livestock.

    black flies - small biting flies that are more common around fresh, flowing water.

    mosquitoes - diseases transmitted by mosquitoes have had a profound impact on human history.

mosquito drawing
mosquito (top and side view)

Lice

The three main types are distinguished by where you find them.

    head lice - head lice are found on the head usually near the scalp.

    body lice - body lice closely resemble head lice but occur more commonly in clothing.

    pubic lice - also called "crabs", these lice occur in pubic areas and are generally considered an STD.

head louse
head louse

Fleas

Fleas (there are many species) tend to be somewhat specific to a particular host animal. The one that most often impacts people and pets is the cat flea. This flea prefers cats and dogs but will also bite people (see this article for life history and control options when homes and pets are infested).

flea
flea

Things that can be mistaken for bug bites

Allergies - since the red itchy skin lesions caused by real bug bites are an allergic reaction to proteins in the bug's saliva it should not be surprising that other types of allergies closely resemble bug bites. Food and respiratory allergies cause hives and itchiness that resemble bug bites as well. In fact, allergies are the number one cause of these skin reactions, they are far more common than real bug bites. For airborne allergens like mold spores the new air purifiers with HEPA filters can be very effective at cleaning the air of contaminants, see this article about air purifiers that remove airborne allergens.

Toxic chemicals - such as cleaning solvents and pesticides can cause severe skin lesions in sensitive individuals. Botanical insecticides are generally safer for indoor use and far less likely to cause problems (they work, too!).

Physical irritants - anything from fiberglass splinters to dry skin can cause irritation. In the case of dry skin a simple room humidifier can give fast, inexpensive relief. Dry, itchy skin is mostly a problem during winter months when central heating in our homes tends to dry the air.

Drug side effects - especially stimulants like amphetamines which are notorious for causing outbreaks of skin lesions caused by scratching to relieve the "crawling" sensations; even prescription drugs can cause these same effects.

Emotional stress and anxiety can cause skin lesions that can resemble bug bites. This may be one of the most common causes but also one that people are generally unwilling to accept. Any recent emotional upset or bout of anxiety that coincides with an outbreak of "bug bites" should be considered suspect.

The bottom line - you should not assume that a "bug" is causing the problem unless you can capture and identify one. In the absence of a verified bug your first step should be to consult with a medical professional to rule out some of the other causes such as allergies. The quicker you find the real cause the faster you'll get some real relief.

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