Hello. Thank you for posting.
Do you mean a fruit fly? Drosophila melanogaster is a species of fly in the family Drosophilidae. The species is known generally as the common fruit fly.
To treat the bite at home, clean the affected area with soap and water. You can apply ice to the area to treat pain. Aloe Vera gel can be applied, topically to ease itching. Allergy medicine like diphenhydramine (Benadryl) can also help if you think you might be having an allergic reaction if the itching is severe.