Blister beetle

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Blister beetles
Hycleus lugens
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Suborder: Polyphaga
Infraorder: Cucujiformia
Superfamily: Tenebrionoidea
Family: Meloidae
Gyllenhal, 1810
Subfamilies

Eleticinae
Meloinae
Nemognathinae
Tetraonycinae

Blister beetles are beetles (Coleoptera) of the family Meloidae, so called for their defensive secretion of a blistering agent, cantharidin. There are approximately 7,500 known species worldwide. Many are conspicuous and some aposematically colored, announcing their toxicity to would-be predators.

Description[edit]

Cantharidin is a poisonous chemical that causes blistering of the skin. Cantharidin is used medically to remove warts[1] and is collected for this purpose from species of the genera Mylabris and Lytta, especially Lytta vesicatoria, better known as "Spanish fly".

Blister beetles are hypermetamorphic, going through several larval stages, the first of which is typically a mobile triungulin. The larvae are insectivorous, mainly attacking bees, though a few feed on grasshopper eggs; while sometimes considered parasitoids, it appears that in general, the meloid larva consumes the immature host along with its provisions, and can often survive on the provisions alone, thus they are not obligatory parasitoids but rather food parasites that are facultatively parasitoid, or simply predatory. The adults sometimes feed on flowers and leaves of plants of such diverse families like Amaranthaceae, Asteraceae, Fabaceae, and Solanaceae.

Toxicity[edit]

Cantharidin is the principal irritant in "Spanish fly," a folk medicine prepared from dried beetles in the Meloidae family.

The largest genus--Epicauta—contains many species that are toxic to horses. A few beetles consumed in a single feeding of alfalfa hay may be lethal.[2] In semi-arid areas of the western United States, modern harvesting techniques may contribute to cantharidin content in harvested forage. The practice of hay conditioning [see Conditioner (farming)]--crushing the stalks to promote drying—also crushes any beetles present and causes the release of cantharidin into the fodder. Blister beetles are attracted to alfalfa and weeds during bloom. Reducing weeds and timing harvests before and after bloom are sound management tactics. Using equipment without hay conditioners may reduce beetle mortality and allow them to escape before baling.[3]

Systematics[edit]

Subfamily Eleticinae[edit]

Tribe Derideini

Tribe Morphozonitini

Tribe Eleticini

Tribe Spasticini

Subfamily Meloinae[edit]

Cysteodemus armatus near Amboy Crater, Mojave Desert, California. Yellow color is flower pollen.

Tribe Cerocomini

Tribe Epicautini

Tribe Eupomphini

Blister beetles like this Lytta vesicatoria (Meloinae: Lyttini) can be safely handled, provided the animal is not startled, and allowed to move around freely. Otherwise, painful poisonings may occur.
Meloe violaceus (Meloinae: Meloini). Note drop of dark orange defensive fluid on thorax.

Tribe Lyttini

Tribe Meloini

Tribe Mylabrini

Yellow-and-black species of Mylabris, one of many known in South Africa as "CMR beetle"

Tribe Pyrotini

Genera incertae sedis

Subfamily Nemognathinae[edit]

Tribe Horiini

Tribe Nemognathini

Tribe Sitarini

Genera incertae sedis

Subfamily Tetraonycinae[edit]

Tribe Tetraonycini

See also[edit]

References[edit]

  1. ^ Bhattacharjee, Pradip; Brodell, Robert T. (2003). "Cantharidin". In Robert T. Brodell and Sandra Marchese Johnson, eds. Warts: Diagnosis and Management—an Evidence-Based Approach. London: Martin Dunitz. pp. 151–160. ISBN 1-84184-240-0. 
  2. ^ University of Arizona VDL Blister Beetle Poisoning in Horses
  3. ^ University of Colorado Extension Blister Beetles in Forage Crops

External links[edit]