What Bit Me

What bit me? 

Bedbugs. Scabies. Fleas. Spiders. Ticks. Lice… All can cause rashes, itching, and a lot of worry. The recent surge in bedbugs in eastern cities has everyone talking about how to find and kill bed bugs. But if you have a new rash or itchy red bumps, how do you know if bed bugs are the cause?  Maybe your skin problem is not even related to insects or bugs and is caused by something different altogether. Many skin disorders like eczema (atopic dermatitis) and/or infections of your pores (known as folliculitis) can have  an itchy rash, and these conditions have nothing to do with biting bugs, although people often wrongly assume that these common skin conditions are “bug” related.

In a practical sense, if you are concerned that you have been bitten by bugs, or you fear that you have bed bugs, you should know what bed bug bites look like, where they tend to bite the skin, and how they compare to other bug bites. These pages may help you determine that you do not have bed bug bites, or, on the other hand, the information presented may encourage you to seek professional assistance.
Though many people will ultimately need assessment, diagnosis, and treatment by a doctor, at skinsight.com you can learn about most of the different types of itchy rashes that result from bugs of all kinds. Skinsight.com also covers dozens of common skin conditions that can look and feel like bug bites but aren’t.

How do I figure out if these are bed bug bites, other types of bites, or something else entirely?

Dermatologists are experts in the diagnosis and treatment of skin problems, including bites, stings, infestations and allergic reactions. When a patient presents to a dermatologist with new skin lesions, the dermatologist looks for visual clues, takes a history, and develops a list of diagnostic possibilities. When there is a new itchy rash, or new itchy red bumps, bug bites might be the cause.

First you should know that only a few insects or bugs actually live on the human skin or hair. They are scabies, body lice, pubic lice, and scalp lice. Rarely, a bug that penetrates the skin during skin exposure to the ground in sandy, tropical areas (cutaneous larva migrans) can travel under the skin and create a rash.

Other bugs can “bite” people but do not live on the body. These biting or stinging insects include mosquitoes, fleas, wasps, bees, and bed bugs.

In our dermatology practice, we have seen patients diagnosed with scabies when in fact they have bed bug bites, or diagnosed with bed bug bites when in fact they were bitten by fleas. If you see or feel a wasp or a mosquito bite you, it is easy to know the diagnosis. But diagnosis of the problem can be difficult when you did not see an actual bug or didn’t feel anything until many hours later.

The most challenging bug-related diagnoses are bed bugs and scabies, because both bed bugs and scabies mites are difficult to see. Bed bugs, though fairly large (pea diameter), are hard to diagnose because the bed bug typically bites at night and then hides in small seams of mattresses, furniture, or the carpet during the day. Most people never see the bed bugs. On the other hand, scabies mites are almost impossible to find due to their size: the scabies mite is much smaller than the period at the end of this sentence.




The tiny scabies mite tunnels very slowly under the outer layer of skin (the stratum corneum), and the body reacts with itchy bumps. Patients and doctors often miss scabies because they mistakenly think that there is a scabies mite at each bump on the skin. In fact, just a handful of mites can cause dozens to hundreds of itchy bumps on the skin. Scabies is diagnosed by finding the very rare and hard to see mite tunnel (known in medical terms as a burrow).

If you have an itchy rash and think you might have scabies, you or your doctor need to look in the areas of the skin where the mite typically creates its burrow. Scabies almost never involves the head. The web spaces between the fingers are said to be the most typical location, but the wrists, palms, and genitals are other important areas in which to look for burrows. In young children and the elderly, the soles of the feet may be involved. The burrow is subtle. Look for linear or curved – almost thready – lesions.

Scabies is contagious!  If you or one of your children has scabies for a while, there is a good chance someone else in the family will develop a scabies infestation as well. Scabies can be difficult for even doctors to diagnose: a typical history, physical examination, and sometimes a “skin scraping” to look for the mite or its eggs may all go into making a diagnosis.  

Bed Bug Bites

bedbug bites

On the other hand, bed bug bites look like bites. They are usually redder and do not have the scale and scratch marks associated with a scabies infection. Bed bugs bites are often very similar to one another in size and shape. The bites are red, fairly round, and usually raised. They occur most frequently on the trunk, because bed bugs like to feed on the warmer parts of the body. Bed bug bites are often grouped near each other, sometimes in a line. Except when there is a heavy infestation, it is unusual to have more than a dozen or so bites or involvement of more than one or two body regions.



Mosquito Bites

Mosquito bites can occur anywhere on exposed skin. Most mosquito bite reactions are small, red, itchybumps that do not last more than two or three days – unlike flea bites, which can persist for more than a week. However, some people have very prominent reactions to mosquito bites. One person may develop large welts or blisters, and the next person might hardly react. All bug bites have a spectrum of reactions that depend upon the individual person’s allergic sensitivity and reaction to the foreign materials left behind by the biting bug.

Tick Bites

tick bites

There are different types of ticks of different sizes and shapes. Some, but not all, can transmit diseases. Most people know that Lyme disease is spread by a tick. The deer tick that spreads Lyme disease is much smaller than the typical tick found on your dog.

The deer tick bite that transmits Lyme disease will often cause an expanding, red, ring-like rash – frequently described as a “bull’s-eye” lesion – at the tick bite site. Untreated Lyme disease can result in spread of the Lyme disease bacteria (Borrelia burgdorferi) in the blood.  On rare occasions, people will develop multiple red rings on the skin from spreading of the initial infection in the blood.

Other ticks can spread other infectious diseases. Some of these ticks can cause severe rashes associated with fever and an illness.

If you have a fever or other symptoms along with a new rash or new skin lesions, especially if there are tiny or larger purple spots that look like bruises, you should see a doctor immediately.



Flea Bites
Flea bites are usually on the lower legs, but they can occur anywhere on the body. Flea bites are usually smaller in diameter, more raised, and longer lasting than bed bug bites. Flea bites are often very firm to the touch and extremely itchy.

Published on 02/15/2011 | Last updated on 10/18/2018