As well as transmitting many important diseases, insect bites produce in their host certain adverse reactions resulting from toxins peculiar to the insect itself. Most insect bites, such as those of the fly, mosquito and flea, cause an almost immediate reaction in humans, consisting of local irritation of the skin which usually subsides without trace within a day. Stinging insects such as the bee, hornet or wasp give rise to painful, elevated skin lesions, that are also transitory for most of the population. For the small percentage which is allergic to bee stings, however, one sting can well be fatal. It is not hard to determine beforehand whether one is allergic or not, but this is not a common procedure. Multiple stings may also give rise to alarming systemic illness, including fainting, difficult breathing, and collapse of the circulatory system, and may result in death. Blood sucking lice, bedbugs, and fleas are more intimately associated with man and live on his body as parasites. Bedbugs live in mattresses, walls, and furniture, and attack their host only in the dark. Lice fix their eggs on hair or clothing and periodically feed on their host. Their bites result in severely itchy skin lesions, which may become infected and result in widespread complications.
250 children in Brazil, the majority under seven years old, died as a result of scorpion stings between 1990 and 1993. During the same period, there were 22,000 reported cases of scorpion stings, with a mortality rate of 1.1 percent.
As an indication of the scale of this problem, the market for bite and burn remedies in the UK in 1986 was £2 million, with a further £2 million for insect repellants.