Blister Beetle Bite: How Serious Is It? Plus Pictures, Treatment, and Prevention

Blister Beetles are a type of arthropod that belong to the order Hemiptera (true bugs). They have six legs and four antennae. Their body is brown or black with white spots. The head is yellowish green, but they sometimes turn into other colors when disturbed. Most species are small insects that live in moist places such as soil, woodpiles, cracks in walls and floors, damp grasses and leaves.

Insects are very common in nature, but some species are considered pests because of their ability to transmit diseases. For example, the European corn borer was introduced to North America from Europe and caused millions of dollars worth of damage to crops. Another insect that causes significant economic losses is the Asian Tiger Mosquito. These mosquitoes carry malaria, dengue fever and yellow fever.

The most dangerous of all insects is the fire ant. Fire ants are capable of causing severe damage to plants and livestock. They feed on plant sap, which can cause crop failure if not controlled. There are several ways to control these insects including pesticides, traps and poisons.

What Are Blister Beetles?

A blister beetle is a large arthropod that belongs to the family Sphecidae (spiders). The name “blister” comes from the ability to produce a blister on human skin by injecting a poisonous substance that can cause a severe allergic reaction. The secretion causes the immune system to create a large raised weal at the site of injection.

Other insects in this family include the sand wasps, thread-waisted wasps and digger wasps. The adult insects have between 0.4 and 2 inches (1 – 5 cm) in length and are black or brownish in color with yellow spots. These insects do not have a waist like other insects.

The female insect lays eggs in the ground and deposits venom into them so that when the larvae hatch they have a ready supply of food. The larvae are legless with a large head and eat the stored venom as well as other insects in the soil.

Blister beetles are mostly found in North America, Northern Africa, South America, Europe, Australia and New Zealand.

Why Do Blister Beetles Sting?

The main reason for the sting of a blister beetle is to defend itself from potential predators. When disturbed, it can also be used in competition with other insects of the same species. Sometimes multiple beetles will attack a single opponent. The main purpose, however, appears to be defense.

Blister beetles are not aggressive and only strike if touched. They can sting repeatedly and the venom can cause an allergic reaction in some people. The effects of the sting can be fatal in some people and cause long-term health problems in others.

Most species of insects in the family have some kind of defensive mechanism and very few are deadly to humans. One of the most dangerous is the South American Urodid sting. A reaction to the venom can cause blindness, paralysis and even death.

Are All Blister Beetles Dangerous?

Most blister beetles are not dangerous to humans and will only cause a minor irritation or swelling when they sting. The danger comes from the allergic reaction that some people have to the poison.

The allergic reaction can be as mild as a small rash or as severe as respiratory failure and death. Most people do not have a serious reaction the first time they are stung. Only those people who have had previous contact with the insect, and developed an allergic reaction, need to be concerned about a more serious reaction on subsequent stings.

Some people are not allergic at all and can handle the insects with no problems. In fact, there are some cultures that use the beetles in ritual healing practices.

The way to treat a blister beetle sting is to apply ice or cold packs to help reduce swelling and take an antihistamine such as diphenhydramine (Benadryl) or tryptanol to reduce the itching and swelling. Most reactions will resolve themselves within 24 hours.

Sources & references used in this article:

Rapid aggressive soft-tissue necrosis after beetle bite can be treated by radical necrectomy and vacuum suction-assisted closure by CME von Goßler, RE Horch – Journal of cutaneous medicine …, 2000 –

Paederus dermatitis: an outbreak on a medical mission boat in the Amazon by JJ Mammino – The Journal of clinical and aesthetic dermatology, 2011 –

Bites and stings of hymenoptera, caterpillar and beetle by VA Green, CJ Siegel – Journal of Toxicology: Clinical Toxicology, 1983 – Taylor & Francis

The clinical characteristics of brown recluse spider bites treated by family physicians by J Cacy, JW Mold – J Fam Pract, 1999 – …

Bullous reactions to bedbug bites reflect cutaneous vasculitis by RD deShazo, MF Feldlaufer, MC Mihm Jr… – The American journal of …, 2012 – Elsevier

Physician’s guide to arthropods of medical importance by J Goddard – 2016 –

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