Ptinus sexpunctatus

Distinguished from other Ptinus species by the combination of: uniform dark body coloration; prominent appressed white scale patches at both basal and apical regions of elytra (creating six spot-like markings); and deeply grooved elytral striae. The subgenus Gynopterus placement may aid identification but requires taxonomic expertise. Similar to other spider beetles in general habitus but the distinct white scale pattern is diagnostic.

Primarily associated with pine forests in its native range. Commensal in nests of cavity-nesting solitary bees (Osmia and Megachile spp.), including artificial bee hotels. Recorded indoors in cosmopolitan settings. Capable of overwintering in unheated outbuildings.

Native to the Palearctic region, found throughout Europe. In the United Kingdom, categorized as 'Nationally Notable B' (31–100 hectads). First recorded as invasive in North America in 2007 (Nova Scotia, Canada), with subsequent records from bee nest contexts. Distribution likely expanding due to commercial bee hotel use.

Larvae feed on food provisions stored by host bees in nests. In laboratory conditions, develops on wheatfeed and fishmeal. Adults require food and drinking water.

• Osmia cornuta - commensal (larvae in nests)possible introduction vector to North America
• Osmia cornifrons - commensal (larvae in nests)possible introduction vector to North America
• Osmia lignaria - commensal (larvae in nests)recorded from Nova Scotia, Canada
• Megachile sp. - commensal (larvae in nests)leaf cutter bee nests in Kent, England
• Lariophagus rufipes - parasitoidectoparasitoid of larvae, recorded in Kent, England

Development at 70% relative humidity: optimum temperature slightly below 30°C, with development completed in approximately 111 days on wheatfeed. Eggs hatch at 30°C. Well-defined diapause occurs as mature larvae in cocoons. Some individuals undergo quiescence as mature adults in cocoons (43.5 days on fishmeal, 103.0 days on wheatfeed at 23°C). Adults live several months. Mean egg output per female: 21.3 eggs at 25°C.

Commensal nesting behavior: larvae inhabit and feed within solitary bee nests. Capable of overwintering in unheated structures. Some adults exhibit quiescence in cocoons before emergence.

Commensal invertebrate associated with cavity-nesting bee communities. Host for ectoparasitoid wasp Lariophagus rufipes. Potential pest of stored products. Population prevalence may be increasing due to rise in artificial bee hotels.

Potential pest in stored products and unheated outbuildings. Invasive species in North America, likely introduced via commercial bee trade (Osmia spp.). Subject of conservation interest in UK (Nationally Notable B status). Increasingly recorded due to popularity of domestic bee hotels.

• Ptinus furSimilar size and habitus, but P. sexpunctatus has distinct white scale patches on elytra and higher optimum development temperature (~30°C vs. ~23°C); P. fur has longer development period, smaller egg output, and more pronounced larval diapause tendency

• spider beetle
• commensal
• bee nest associate
• invasive species
• stored product pest

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Studies on Beetles of the Family Ptinidae. VI.—The Biology ofPtinus fur(L.) andP. sexpunctatusPanzer
• Lariophagus rufipes Hedqvist (Hymenoptera: Chalcidoidea: Pteromalidae) reared from Ptinus sexpunctatus Panzer (Coleoptera: Ptinidae) in nesting tubes occupied by Megachile sp. leaf cutter bees (Hymenoptera: Apoidea) in Kent, England