Reesa vespulae

Distinguished from other dermestid pests by its elongated rather than rounded body shape, the orange-oblique band on the elytra below the shoulder, and yellow-brown leg coloration. The combination of yellow elytral fasciae against a dark brown background separates it from Attagenus species (uniformly dark) and most Anthrenus species (more rounded with variable patterning). The four-segmented brown antennal club differs from some related genera. All specimens are female; no males have been found.

Small beetle measuring 2.5–4 mm in length with an elongated, somewhat flattened body. Coloration is black-brown overall, covered with large brown setae except for distinct yellow elytral fasciae. Elytra are brown with an orange-oblique band below the shoulder. Legs are yellow-brown, with tibiae and tarsi matching this coloration. Antennae have articles 2–6 yellow-brown, terminating in a brown four-segmented club. Body shape is more elongate than the rounded form typical of Anthrenus carpet beetles.

Indoor environments associated with human structures: museums, historic houses, libraries, art galleries, store rooms, food warehouses, and private dwellings. Specific microhabitats include accumulations of fluff and dust beneath furniture, spaces under display cases, dead birds in roof areas, and wasp nests on building exteriors. Development occurs in dry, undisturbed locations with access to proteinaceous materials.

Native to North America, originally described from Minnesota. Introduced to Europe beginning in the 1950s (first UK record 1970s), New Zealand by 1942, and subsequently spread to Australia, South America, and North Africa. Now established throughout much of Europe with increasing detection in museum environments since 2014.

Adult activity occurs year-round in heated indoor environments. Trapping data shows adults and larvae more frequently detected during active infestations. No true seasonal dormancy; development rate depends entirely on temperature with slower progression in cooler conditions.

Larvae feed on dried animal and plant materials including hides, furs, leather, wool, dried plants, and stored grain or cereal products. In museum collections, larvae show marked preference for Coleoptera and Lepidoptera specimens over other zoological materials.

Development is temperature-dependent: 1–1.5 years at 25°C, 2 years at 23°C, and 3 years at 15–21°C. No development occurs below 13°C. Eggs hatch after approximately 3 weeks at 18°C. Adults live 6–14 days at room temperature. Females begin oviposition after 2–3 days, producing approximately 24 eggs. Obligate parthenogenesis allows population establishment from a single individual.

Larvae range widely in search of food when population density is high. Adults are attracted to light and found against windows in morning. Parthenogenetic reproduction enables rapid colonization of new sites without mating. Typically detected as adults in small populations, but larvae predominate where infestations are dense.

Pest species in anthropogenic environments. Damages natural history collections, herbaria, and stored food products. Serves as an indicator of inadequate environmental management in heritage institutions.

Significant economic pest of museum and heritage collections, causing irreversible damage to irreplaceable scientific and cultural specimens. Subject to monitoring and control programs in Austrian museums, where found in approximately 30% of monitored buildings. Control relies on freezing or anoxia treatments; pesticide use restricted in EU. Parthenogenesis facilitates spread through international trade and travel.

• Attagenus unicolor (black carpet beetle)Uniformly dark coloration without yellow elytral fasciae; more rounded body shape
• Anthrenus spp. (museum carpet beetles)Rounded body form with variable patterning but lacking the orange-oblique shoulder band and elongated shape of Reesa
• Trogoderma variabile (warehouse beetle)Larger size with different elytral patterning; males present in populations

• dermestid
• museum pest
• parthenogenetic
• stored product pest
• heritage pest
• cosmopolitan
• North American origin

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• New Analysis Refines Taxonomy of Dermestid Beetles
• dermestid beetles - Entomology Today
• Un nouvel hôte des habitations lyonnaises, le Coléoptères ravageur Reesa vespulae (Dermestidae)
• Catch of Reesa vespulae in Heritage Environments.