What are the lumps that look like mosquito bites?

Understanding Hives

The lumps that resemble mosquito bites are known as hives, or wheals (also called welts). These slightly elevated, red skin patches can appear in clusters on various parts of the body and often provoke itching, though they may sometimes cause a stinging sensation as well. The clinical term for hives is urticaria (er-tuh-care-ia).

For more information, refer to Kids Health Info: Hives - The Royal Children.