Family Meloidae - Blister Beetles
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Coleoptera (Beetles)
Suborder Polyphaga (Water, Rove, Scarab, Long-horned, Leaf and Snout Beetles)
Superfamily Tenebrionoidea (Fungus, Bark, Darkling and Blister Beetles)
Family Meloidae (Blister Beetles)
Synonyms and other taxonomic changes
Explanation of Names
Family name from Meloe
, which see.
The name Meloidse is of uncertain derivation. The larger, more bulky species, belonging to the genus Meloe, when alarmed exude from the joints of the legs a yellowish oily liquid, whence the name "oil beetles," often applied to them. To our more common forms the name "blister beetles" is given, on account of their possessing a peculiar principle called cantharidine which, when extracted and applied to the human skin, possesses the power of raising blisters.
ca. 410 spp. in 22 genera in our area, ~2500 spp. in 120 genera worldwide(2)
Overview of our fauna:
Taxa not yet in the guide are marked (*)
Incertae sedis *Spastonyx
, typically 10-20 mm
Medium to large beetles, typically elongated and rather cylindrical, often found on flowers, foliage.
Head broad, generally rectangular when viewed from above.
Pronotum cylindrical and narrower than both the head and base of elytra.
Elytra not flat, typically rolled over abdomen.
Body soft, somewhat leathery.
Antennae filiform (thread-like) or moniliform (beaded).
Tarsi 5-5-4; claw either toothed or lobed.
Blister beetles of e. US are generally dull in color; western ones often very colorful(4)
, apparently aposematic
Key to New World genera in(5)
worldwide and across NA, with greatest diversity in arid/semiarid areas (sw. US)(2)
For larval food, most utilize the provisions and larvae of native ground nesting bees (esp. Megachilidae
); several genera (in our area, Epicauta & Linsleya
) utilize grasshopper eggs (Acridoidea)(3)
. Adults feed on leaves and flowers of several families of plants, particularly Asteraceae, Fabaceae, and Solanaceae(2)
Life cycle is hypermetamorphic
. Larvae are parasitoids. 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)(4)(6)
In some cases, e.g. in Meloe
, triungulins aggregate and attract male bees with chemical signals (Saul-Gershenz & Millar 2006
Pressing, rubbing, or squashing blister beetles may cause them to exude hemolymph which contains the blistering compound cantharidin
. Ingestion of blister beetles can be fatal. Eating blister beetles with hay may kill livestock. Cantharidin is commercially known as Spanish Fly.
Males of some other beetles (notably, Pedilus
and some Anthicidae
) seek out blister beetles, climb onto them and lick off the exuded cantharidin. These other beetles, resistant to the toxic effects, use the agent to impress their females; the cantharidin is transferred to the female with the sperm packet during mating. The eggs the female lays are coated with cantharidin to protect them from predators. Some plant bugs (e.g. Aoplonema
) are also attracted to meloid beetles.
(based on Jim McClarin's comment)
In similar families, head is usually not
wider than pronotum (4)
Soldier Beetles (Cantharidae)
: elytra usually flat, not rolled
Fire-colored Beetles (Pyrochroidae)
: antennae saw-like (serrate) or comb-like (pectinate)
Overview of FL fauna
] by Selander & Fasulo(8)
(world fauna, gallery)
|2.||American Beetles, Volume II: Polyphaga: Scarabaeoidea through Curculionoidea|
Arnett, R.H., Jr., M. C. Thomas, P. E. Skelley and J. H. Frank. (eds.). 2002. CRC Press LLC, Boca Raton, FL.
|3.||Blister beetles (Coleoptera: Meloidae) of Wisconsin: distribution and ecology|
Marschalek D.A. 2013. University of Wisconsin - Madison. PhD dissertation. viii+349 pp.
|4.||Peterson Field Guides: Beetles|
Richard E. White. 1983. Houghton Mifflin Company.
|6.||Introduction to North American Beetles|
Charles S. Papp. 1984. Entomography Pubns.
|7.||Field Guide to Beetles of California|
Arthur V. Evans and James N. Hogue. 2006. University of California Press.