Blister beetle

Definition

Any beetle of the family Meloidae, characterized by soft, flexible elytra and the production of cantharidin, a potent blistering agent secreted as a chemical defense against predators. The approximately 2,500 species worldwide range from small to moderately large and often display aposematic (warning) coloration advertising their toxicity. Cantharidin persists in dried beetles and is highly toxic to horses and other livestock when ingested in contaminated hay, making blister beetles significant in veterinary entomology.

Etymology

From the characteristic blistering skin reaction caused by their defensive secretion cantharidin

Example

The striped blister beetle Epicauta vittata is a common alfalfa pest whose aggregations can poison horses when baled into hay; the Spanish fly Lytta vesicatoria, historically misused as an aphrodisiac, is another well-known meloid.

Synonyms

• meloid

Related Terms

• Cantharidin
• Meloidae
• aposematic coloration
• defensive secretion
• Spanish fly
• Epicauta
• Lytta
• Hypermetamorphosis
• toxicology

Usage Notes

In veterinary contexts, 'blister beetle' specifically signals poisoning risk rather than mere identification. The family Meloidae is sometimes called 'blister beetles' collectively, but specialists reserve the common name for adults; larvae are typically called triungulins or hypermetamorphic larvae. Not all meloids are brightly colored—some are cryptic—so color alone does not confirm identification. The term 'Spanish fly' properly refers to specific Lytta species but is often misapplied broadly.