Impressive meloine beetle

Conservation Status

IUCN Red List

not listed

NatureServe

NNR - Unranked

Minnesota

not listed

Description

Impressive meloine beetle is an elongated, medium-sized, oil beetle, ½″ to 1″ in length. Males are smaller than females.

The head, body, and legs are usually brilliant metallic blue, violet, or green, sometimes black.

The head is more or less rectangular when viewed from above. It is 70% to 80% as long as wide and is abruptly constricted behind the eyes forming a short neck. It is sparsely covered with scattered, fine pits. The upper margin of the eye is nearly straight. The antennae are bead-like and have 11 rounded segments. On males, the antennae are bent in the middle with segments 5, 6, and 7 forming a C-shaped kink. Segment 5 is enlarged and flared outward at the end.

The thorax is narrower than the head and abdomen. The upper plate covering the thorax (pronotum) has straight sides that converge toward the rear (posteriorly). It is sparsely covered with scattered, fine pits.

The abdomen is oval-shaped. There are no hindwings. The hardened forewings (elytra) are small, much shorter than the abdomen, and overlap at the base.

The legs are long and slender. The femur of the front leg does not have a patch of hair. A outer spur at the end of the fourth leg segment (tibia) of the hind leg projects toward the rear.

Size

Total length: ½″ to 1″

Similar Species

Habitat

August to October

Ecology

Season

Behavior

They are found on the ground or on low foliage.

When threatened or mishandled blister beetles (family Meloidae) exude a yellowish liquid from their joints. The thick oily substance contains the toxin cantharidin, which causes blistering on human skin.

Life Cycle

The female deposits eggs on foliage or in a 1″ deep burrow in the ground. After the eggs hatch the larvae pass through four stages. The first stage (triungulin) is mobile on plants. The entire hatched group climbs to the top of a plant and forms a cluster in roughly the shape of a female ground bee. It then exudes a chemical scent that mimics the pheromone of a female bee. When a male bee attempts to mate with the mass, some of the larvae attach themselves to its hairs. When the male mates with a female bee some of the larvae attach to the female. These remain on the female while she builds a nest, then detach and begin feeding on newly laid bee eggs. The second stage of this larva is a short-legged grub, called “first grub”, that spans four molts (instars). This stage feeds on honey in the nest. The third stage/sixth instar, called coarctate, is legless and immobile. The larva usually overwinters in this stage is a state of low metabolic activity (diapause), though it may overwinter in other stages. The fourth stage/seventh instar, called “second grub”, is a nonfeeding form that resembles the first grub. This stage feeds on honey and stored pollen. it is soon followed by the pupal stage.

Favorable environmental conditions may cause the larva to skip the coarctate stage. Adverse conditions may cause it to molt from the second grub back to the first grub, delaying the pupal stage until conditions improve.

Larva Food/Hosts

Bee eggs and stored food in ground-nesting bee nests.

Adult Food

Plant foliage and flowers of many plants, including field mustard, hepatica, spotted touch-me-not, tall buttercup, bristly buttercup, Irish potato, virgin’s bower, and eastern white pine.

Distribution

Sources

7, 24, 30, 82, 83.

Biodiversity occurrence data published by: Minnesota Biodiversity Atlas (accessed through the Minnesota Biodiversity Atlas Portal, bellatlas.umn.edu. Accessed 9/24/2026).

Meloe impressus Kirby, 1837 in Bánki, O., Roskov, Y., Döring, M., Ower, G., Hernández Robles, D. R., Plata Corredor, C. A., Stjernegaard Jeppesen, T., Örn, A., Pape, T., Hobern, D., Garnett, S., Little, H., DeWalt, R. E., Miller, J., Orrell, T., Aalbu, R., Abbott, J., Abreu, C., Acero P, A., et al. (2026). Catalogue of Life (2026-08-26 XR). Catalogue of Life Foundation, Amsterdam, Netherlands. https://doi.org/10.48580/dgyy9

The bionomics of blister beetles of the genus Meloe and a classification of the New World species [by] John D. Pinto and Richard B. Selander. Pinto, John D.; Selander, Richard Brent, 1927. joint author. University of Illinois Press 1970