Scanning electron micrograph of the serrated sting of the common wasp, Vespula vulgaris. The sting introduces around 50 microgrammes of venom into the skin, causing inflammation and localised pain. This is only dangerous if the resulting swelling obstructs breathing or if the victim is allergic to the venom. In addition to a number of allergenic compounds the venom contains substances such as 5-hydroxytryptamine, bradykinin, catecholamines and cholinesterase. The application of an antihistamine cream relieves the irritation caused by the sting by counteracting the increased flow of histamine in the tissues which results. Magnification: x120 at 10x8 inch size.