Bug bites itch because of a mild immune system reaction to bug saliva, according to the Mayo Clinic. When a bug bites someone it injects its saliva into the skin and the reaction in the body's immune system can result in an itchy bump.
According to MedicineNet.com, bug bites can cause itching as well as redness, mild burning, localized and minor pain, and swelling. Most of these bug bite symptoms will not last more than a day or two; these more benign bug bites are usually caused by bugs such as mosquitoes, bed bugs, ticks, fleas, chiggers, mites, lice, nonpoisonous spiders, and some biting ants and flies.
The best way to deal with bug bites is to focus on avoiding getting bitten, according to MedicineNet.com. Several ways exist to avoid bug bites. The Centers for Disease Control recommends dressing in long-sleeved shirts and long pants to minimize skin exposure, using insect repellent on exposed clothing and skin, and avoiding peak biting hours (dawn and dusk) and places with heavy insect populations (tall grasses and densely wooded or vegetated areas).
Once bitten, MedicineNet.com suggests anti-itch remedies, such as applying a paste of baking soda and water, calamine lotion, or creams containing hydrocortisone or lidocaine. Taking Benedryl or other over-the-counter medications containing diphenhydramine can also relieve itching and pain caused by bug bites.