Genus Chlaenius - Vivid Metallic Ground Beetles

Chlaenius Bonelli, 1810

From Greek chlaen cloak (Word Roots and Combining Forms). This likely refers to the fine pubescence of the dorsal surface.

Nearctica (1) lists 51 North American species.

Arnett, p. 391, lists 50 species (2).

8-23 mm

Medium sized to large ground beetles. Attractive, often with vivid metallic coloration of head, pronotum. Pronotum has distinctive "punctures" (indentations). Head, pronotum, and elytra have fine hairs (setae), thus are called "setose" in technical language. Front tarsomeres 1-3 of male are dilated, have spongy underside, presumably used in mating (3) (4).

They are covered with hairs that lie flat.(5)

Some images showing these characteristics:

Reported to smell foul when disturbed (like leather), therefore probably have strong chemical defenses, like many in this family.

Much of North America? Perhaps 20 species in east.

Usually moist areas, some semiaquatic.

Typically spring-early summer, again in late summer-fall.

Predatory.

Some species lay eggs in mud cells place on underside of leaves or twigs. Cell morphology can be distinctive for a species. Presumably most species have one generation per year, with adults overwintering to breed in spring. Come to lights.

Ground Beetles of Canada illustrates several species--these are the best photographs

Insects of Cedar Creek--2 spp

Insects of Quebec