Family Meloidae - Blister Beetles

Meloidae Gyllenhaal 1810

Origin unclear, maybe from Greek meloe, meloi 'probe'(1)

ca. 410 spp. in 22 genera in our area, ~2500 spp. in 120 genera worldwide(2)

Overview of our fauna:

Family MELOIDAE

Taxa not yet in the guide are marked (*)

Subfamily Meloinae

Tribe Pyrotini Pyrota

Tribe Eupomphini Cordylospasta, Cysteodemus, Eupompha, Megetra, Phodaga, Pleuropasta, Tegrodera

Tribe Epicautini Epicauta, Linsleya

Tribe Lyttini Lytta

Tribe Meloini Meloe

Incertae sedis *Spastonyx

Subfamily Tetraonycinae

Tetraonyx

Subfamily Nemognathinae

Tribe Horiini Cissites

Tribe Nemognathini Gnathium, *Hornia, Nemognatha, Pseudozonitis, Rhyphonemognatha, Tricrania, Zonitis

3-30 mm, typically 10-20 mm

Blister beetles of e. US are generally dull in color; western ones often very colorful(3), apparently aposematic.

Key to New World genera in(4)

Short-winged forms

Diversity is greatest in arid and semiarid areas (sw. US)(2)

Adults feed on leaves and flowers of several families of plants, particularly Asteraceae, Fabaceae, and Solanaceae(2)

Life cycle is hypermetamorphic. Larvae are parasitoids. Hosts include bees of families Megachilidae and Andrenidae. Epicauta (and other genera) larvae prey on eggs of grasshoppers. Eggs are laid in batches in soil near nests of hosts, sometimes in nest of bee host, or on stems, foliage, or flowers. Larvae undergo hypermetamorphosis--first instar larvae (usually called triungulins) are active, have well-developed legs and antennae. These typically search for hosts. Later instars tend to have reduced legs and be less active, having found hosts. There is a coarctate (pseudopupal) stage, which is usually how the larvae overwinter. Life cycle may be as short as 30 days, or as long as three years. It is typically one year, corresponding to that of host(2)(3)(5).

In some cases, e.g. in Meloe, triungulins aggregate and attract male bees with chemical signals (Saul-Gershenz & Millar 2006).

Pressing, rubbing, or squashing adult blister beetles may cause them to exude their hemolymph (“blood”), which contains cantharidin. This compound causes blistering of the skin, thus the name blister beetle. Accidental or intentional ingestion of these insects can be fatal. There are documented incidents of horses dying after eating hay in which blister beetles were inadvertently baled with the forage. Watch that curious children do not attempt to put these beetles in their mouths. The external use of cantharidin, commercially known as "Spanish fly," the supposed aphrodisiac, is likewise discouraged.

In similar families, head is usually not wider than pronotum (3):

J.D. Pinto and M.A. Bologna. The New World genera of Meloidae (Coleoptera) a key and synopsis. 1999. J. Nat. Hist. 33:569-620.

J. D. Pinto, "A Taxonomic Review of Cysteodemus, Phodaga, and Pleuropasta with a New Generic Synonymy ", Proc. Entomol. Soc. Wash., 86(1), 1984, pp. 127-143.

Evans & Hogue(6)