Why do insect bites itch?


August 3, 2017

As summer continues and mosquito control applications increase, pest management customers may ask technicians this common question: “Why do bug bites itch?”

It may serve your business’ reputation well to have the answer in your arsenal.


When a mosquito bites, its saliva is injected as it pierces the skin, according to Dr. Jorge Parada, medical advisor to the National Pest Management Association. This is true for stinging insects as well.

The saliva is made up of various proteins foreign to the human body, so the immune system responds by releasing histamine — a chemical that allows white blood cells and proteins. (Antihistamines medications treat allergies and itches.)

That means itching and swelling is a positive reaction — if there was no response like this to a bite or sing, it means your weak immune system is weak and you are susceptible to an infection. That isn’t to say swelling and itchiness isn’t irritating.


“From someone who has a very huge reaction to mosquito bites, it is difficult not to scratch,” says Dr. Jennifer T. Haley, a dermatologist in Maryland.

By scratching, the mosquito saliva gets stirred up, heightening the histamine response. Also, the skin could break, allowing bacteria to infect the area.

“If you can’t resist the urge, at least try the safer alternative of rubbing the itchy area with the palm of your hand,” Dr. Dheeraj Taranath, regional medical director of MedExpres, told Reader’s Digest.

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