Species Anthrenus verbasci - Varied Carpet Beetle

Variegated Carpet Beetle, Varied Cabinet Beetle, Small Cabinet Beetle

Anthrenus verbasci (Linnaeus 1767)

1.7‒3.5 mm(1)

Dorsal surface with scales of two colours: white and yellowish brown (may change to grey in older specimens). White scales condensed on lateral margins of pronotum, a prescutellar spot on the hind margin, and in several spots on elytra, usually partly merging into three tranverse fasciae.

Important characters apart from colour: Eyes not notched in front (diagnostic vs. A. flavipes and A. parvus), antennae 11-segmented with club of three segments (diagnostic vs. A. coloratus)

A. flavipes has eyes notched anteriorly and similar colour pattern, but without distinct prescutellar spot on pronotum, white scales on sides of pronotum usually divided into 2-3 patches, elytra with a distinct white spot on base, but not adjacent to scutellum.

A. coloratus has 9-segmented antennae:

Cosmopolitan, adventive in NA (introduced ca. 1850), common throughout US and adjacent Canada (abundant in coastal BC, occasional in ON, rare elsewhere)(2)(3)

adults found outdoors on various flowering plants, esp. Spiraea(4); primarily a household pest on plant (dried fruits/nuts) and animal materials; regularly encountered in dried-milk factories, occasionally in flour mills and warehouses (2); outdoors, in bird nests and wasp nests in attics, and under siding; also in bat roosts.

Field strains have an apparent diapause and must experience cold temperatures to produce adults in the spring; household strains produce adults in the fall(4)

all sorts of materials of animal origin (wool, fur, skins...)(2), incl. dry insect specimens; stored food materials and products (biscuits, cakes, seeds, wheat, maize, oats, rice, cayenne pepper, cacao, and dried cheese); adults feed on pollen(4)

The most abundant species in buildings; arguably, world's most important pest of insect collections. Adults from indoor populations have a negative attraction to light, but near the end of their oviposition period they become attracted to light. Adults from outdoor populations show attraction to light. Adults are active fliers and often fly high above the ground. They enter houses through open windows, around eaves, soffits, and attic vents, and often lay eggs in the dead insects collecting in light fixtures.(4)(2)