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Insect Bites

Insect Bites Definition

Stings and bites from insects are common. They often result in redness and swelling in the injured area. Sometimes a sting or bite can cause a life-threatening allergic reaction or transmit pathogens (viruses, bacteria or parasites, for example) to humans.

Arthropods are insects that live primarily on land and have six legs. They dominate the present-day land fauna. They represent about three-fourths of known animal life. In fact, the actual number of living species is not known and is estimated to be over 10 million.

The orders that contain the greatest numbers of species are:

  • Coleoptera (beetles),
  • Lepidoptera (butterflies and moths),
  • Hymenoptera (ants, bees, wasps), and
  • Diptera (true flies).

However, the majority of people lump insects, arthropods, and anything small that bites or stings as a "bug" or an insect. The goal of this article is to provide an overview of biting and stinging insects or bugs without making strict scientific definitions of insects or bugs. The article covers the predominant biting and stinging bugs seen or imported to the US recently, but does not cover every possible stinging or biting bug or insect worldwide.

Insect Bites causes

Most insects do not usually attack humans unless they are provoked. Many bites and stings are defensive. Insects sting to protect their hives or nests or when incidentally touched or disturbed (so hives and nests should not be disturbed or approached).

A sting or bite injects venom composed of proteins and other substances that may trigger an allergic reaction in the victim. The sting also causes redness and swelling at the site of the sting.

Bees, wasps, hornets, yellow jackets, and fire ants are members of the Hymenoptera family. Bites or stings from these species may cause serious reactions in people who are allergic to them. Death from bee stings is 3 to 4 times more common than death from snake bites. Bees, wasps, and fire ants differ in how they inflict injury.

  • When a bee stings, it loses the entire injection apparatus (stinger) and actually dies in the process.
  • A wasp can inflict multiple stings because it does not lose its injection apparatus after it stings.
  • Fire ants inject their venom by using their mandibles (the biting parts of their jaw) and rotating their bodies. They may inject venom many times.
  • Puss caterpillars (Megalopyge opercularis or asp) have hollow "hairs" or spines (setae) that break when touched and toxin is injected into the skin.
  • In contrast, bites from mosquitoes are not defensive; mosquitoes are looking to get blood for a meal. Typically, most mosquitoes do not cause significant illnesses or allergic reactions unless they convey "vectors," or pathogenic microorganisms that actually live within the mosquitoes. For instance, malaria is caused by an organism that spends part of its life cycle in a particular species of mosquitoes. West Nile virus is another disease spread by a mosquito. Various mosquitoes spread other viral diseases (such as equine encephalitis; dengue and yellow fever to humans and other animals).

Other types of insects or bugs that bite for a blood meal and diseases that are possibly transmitted are as follows:

  • Lice bites can transmit epidemic relapsing fever, caused by spirochetes (bacteria).
  • Leishmaniasis, caused by the protozoan Leishmania, is carried by a sand fly bite.
  • Sleeping sickness in humans and a group of cattle diseases that are widespread in Africa, and known as, are caused by protozoan trypanosomes transmitted by the bites of tsetse flies.
  • Bacteria-caused diseases tularemia can be spread by deer fly bites, the bubonic plague by fleas, and the epidemic typhus rickettsia by lice.
  • Ticks (arachnids) can transmit Lyme disease and several other illnesses through their bites; ticks bite so they can obtain a blood meal.
  • Other arachnids (bugs) such as chiggers, bedbugs, and mites typically cause self-limited localized itchiness and occasional swelling.
  • Serious bites from spiders (arachnids), which are not insects, can be from the black widow or brown recluse spiders; the spiders bite usually as a defense mechanism.

Other insects and bugs can transmit diseases by simply transferring pathogens like Salmonella spp by contact. For example, in unsanitary conditions, the common housefly can play an incidental role in the spread of human intestinal infections (such as typhoid, bacillary and amebic dysentery) by contamination of human food as it lands and "walks" over foods after previously "walking" on contaminated items like feces.

Medically Reviewed by a Doctor on 7/7/2014

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Insects bites causes and symptoms

Some insects are more likely than others to cause allergic or toxic reactions.

  • A bee leaves the stinger behind and then dies after stinging. Africanized honeybees, the so-called killer bees, are more aggressive than common honeybees and often attack together in great numbers.
  • Wasps, including hornets and yellow jackets, can sting over and over. Yellow jackets cause the greatest number of allergic reactions.
  • A fire ant attaches to a person by biting with its jaws, then, pivoting its head it stings from its abdomen in a circular pattern at multiple sites.

Bites and stings are more serious if you develop one or more of the following conditions after an insect or spider bite or sting:

  • A severe allergic reaction (anaphylaxis)
  • A toxic reaction
  • A large skin reaction
  • Signs of a skin infection
  • Serum sickness


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