Oil-beetle
Guides
Meloe
Oil Beetles
Meloe is a large genus of blister beetles commonly known as oil beetles, named for their defensive release of oily hemolymph containing cantharidin from leg joints and other body articulations when disturbed. Adults are flightless with shortened elytra that expose most of the abdomen, often displaying iridescent blue, green, or black coloration. The genus exhibits hypermetamorphic development with triungulin larvae that employ phoretic transport on bees to access host nests, where they consume provisions and host offspring.
Meloe americanus
Buttercup Oil Beetle, American Oil Beetle
Meloe americanus is a flightless blister beetle native to North America, commonly known as the buttercup oil beetle or American oil beetle. Adults are entirely black with occasional blue metallic iridescence, measuring 7–17 mm in length. The species exhibits a complex life cycle involving hypermetamorphosis, with triungulin larvae employing phoresy to reach host bee nests where they develop as parasites. Adults are active during late autumn through early spring, with peak emergence in December and April. The beetle is notable for its chemical defense: it secretes cantharidin, a potent blistering agent toxic to mammals at high concentrations.
Meloe angusticollis
short-winged blister beetle, oil beetle
Meloe angusticollis is a North American blister beetle known for its short elytra that leave most of the abdomen exposed. Adults release cantharidin-laden hemolymph as a chemical defense, which causes skin blistering in humans. The species exhibits hypermetamorphosis, with mobile first-instar larvae (triungulins) that parasitize solitary bees by hitchhiking to nest sites. Females are notably larger than males, reaching up to 19 mm.
Meloe barbarus
oil beetle
Meloe barbarus is a species of blister beetle in the family Meloidae, first described by LeConte in 1861. It belongs to the subgenus Treiodous within the genus Meloe. The species is found in North America, with collection records from western regions including British Columbia, Canada. Like other oil beetles in the genus Meloe, it possesses defensive chemical compounds and exhibits complex life history traits involving parasitism of ground-nesting bees.
Meloe carbonaceus
oil beetle
Meloe carbonaceus is a species of blister beetle (family Meloidae) described by LeConte in 1866. The species is known from North America, with records from Alberta, Canada. Like other members of the genus Meloe, it is commonly referred to as an oil beetle. The species is represented by limited specimen holdings in museum collections.
Meloe dianella
Meloe dianella is a species of blister beetle (family Meloidae) first described by Pinto and Selander in 1970. It belongs to the genus Meloe, commonly known as oil beetles, which are characterized by their defensive production of cantharidins. The species is known from North America, with records from Canada (Alberta, British Columbia, and Nova Scotia). Like other members of its genus, it is presumed to have a parasitic life cycle involving solitary bees, though specific details for this species remain undocumented.
Meloe dugesi
Meloe dugesi is a species of blister beetle (family Meloidae) described by Champion in 1891. It belongs to the genus Meloe, commonly known as oil beetles, which are characterized by their defensive production of cantharidins. The species occurs in Central America and North America. Like other members of its genus, it likely exhibits the typical Meloe life cycle involving triungulin larvae that parasitize solitary bees.
Meloe franciscanus
Meloe franciscanus is a blister beetle endemic to the southwestern United States. Adults are flightless and feed on Astragalus lentiginosus. The species is notable for its highly specialized larval parasitism of solitary bees in the genus Habropoda. First described from San Francisco dunes in 1928, the species was presumed locally extirpated there due to habitat loss but persists in other regions.
Meloe impressus
blister beetle, oil beetle
Meloe impressus is a species of blister beetle in the family Meloidae, native to North America. It belongs to a genus commonly known as oil beetles, characterized by their defensive secretion of cantharidin, a potent blistering agent. The species is recorded across western and central Canada and the United States. Like other Meloe species, it likely exhibits the complex life history involving parasitic larvae that exploit solitary bees as hosts, though specific details for this species remain poorly documented.
Meloe strigulosus
Meloe strigulosus is a blister beetle in the family Meloidae, characterized by its phoretic larval behavior involving attachment to other organisms for transport. The species has been documented in coastal dune habitats in Oregon, where its ecological relationships have been specifically studied. Adults possess the typical oil beetle morphology with shortened elytra that expose much of the abdomen. Like other Meloe species, it produces cantharidin, a defensive compound toxic to vertebrates.