A bug bite occurs when an insect, such as a mosquito, bee, or ant, pierces the skin to feed on blood or inject venom. This can lead to localized swelling, redness, and itching as the body's immune system reacts to the foreign substances introduced by the insect. Most bug bites are harmless and can be treated at home with over-the-counter remedies like antihistamines or hydrocortisone cream. However, some bites can cause allergic reactions or transmit diseases, making it important to seek medical attention if symptoms worsen or if a tick bite is suspected.