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Family Meloidae - Blister Beetles

white-ringed black beetle - Epicauta segmenta Red Blister Beetle - Lytta nitidicollis Blister beetle - Gnathium minimum Unknown meloid? - Epicauta ferruginea unknown beetle - Megetra vittata Blister Beetle - Nemognatha scutellaris Lytta sp. - Weld County, Colorado - Lytta - male Is this another Pyrota akhurstiana - Pyrota akhurstiana
Classification
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)
Explanation of Names
Meloidae Gyllenhaal 1810
the name "blister beetles" refers to the ability of causing skin blisters if handled (the beetle's body contain the toxic substance, cantharidin)
Numbers
ca. 410 spp. in 22 genera in our area, ~2500 spp. in 120 genera worldwide(1)
Overview of our fauna:
Family MELOIDAE
Subfamily Meloinae
Tribe Lyttini Lytta
Tribe Meloini Meloe
Incertae sedis Spastonyx
Subfamily Nemognathinae
Size
3-70 mm(2), typically 10-20 mm
Identification
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(3), apparently aposematic.
Key to New World genera in(4)
Short-winged forms
Range
worldwide and across NA, with greatest diversity in arid/semiarid areas (sw. US)(1)
Food
For larval food, most utilize the provisions and larvae of native ground nesting bees (esp. Megachilidae & Andrenidae); several genera (in our area, Epicauta & Linsleya) utilize grasshopper eggs (Acridoidea)(2). Adults feed on leaves and flowers of several families of plants, particularly Asteraceae, Fabaceae, and Solanaceae(1)
Life Cycle
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(1)(3)(5).
Triungulins of some meloids, e.g. in Meloe, aggregate and attract male bees with chemical signals (Saul-Gershenz & Millar 2006).
Remarks
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)
See Also
In similar families, head is usually not wider than pronotum (3):
Soldier Beetles (Cantharidae): elytra usually flat, not rolled
Fire-colored Beetles (Pyrochroidae): antennae saw-like (serrate) or comb-like (pectinate)
Print References
(6)
Internet References
Overview of FL fauna (Selander & Fasulo)(7)
image gallery & info on world fauna in(8)
Works Cited
1.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.
2.Blister beetles (Coleoptera: Meloidae) of Wisconsin: distribution and ecology
Marschalek D.A. 2013. University of Wisconsin - Madison. PhD dissertation. viii+349 pp.
3.Peterson Field Guides: Beetles
Richard E. White. 1983. Houghton Mifflin Company.
4.The New World genera of Meloidae (Coleoptera): a key and synopsis
Pinto J.D., Bologna M.A. 1999. J. Nat. Hist. 33: 569-620.
5.Introduction to North American Beetles
Charles S. Papp. 1984. Entomography Pubns.
6.Field Guide to Beetles of California
Arthur V. Evans and James N. Hogue. 2006. University of California Press.
7.U. of Florida and Dep. of Agriculture Website
8.Meloidae.com