Insects Bites & Stings: can be divided into 2 groups venomous insect such as a bee or wasp, which uses this as a defense mechanism by injecting toxic and painful venom through its stinger. Non-venomous insect bites pierce the skin to feed on blood. This usually results in intense itching. Papular Urticaria: common disorder manifested by chronic or recurrent papules caused by a HYPERSENSITIVITY REACTION to the bites of mosquitoes, fleas, bedbugs, and other insects