Pleocoma hirticollis vandykei

As a subspecies of P. hirticollis, distinguishing P. h. vandykei from other subspecies requires examination of subtle morphological characters, likely involving differences in setal density, pronotal shape, or male genitalia. The species P. hirticollis as a whole is characterized by males with lamellate, fan-like antennae and a densely setose pronotum. Females are flightless and have reduced elytra, exposing several abdominal segments. Specific diagnostic features for vandykei remain undocumented in widely accessible sources.

North America; precise range within the distribution of P. hirticollis is not well documented in available sources, though the parent species occurs in California and Oregon.

Adults have been observed in October, consistent with the autumn emergence pattern typical of Pleocoma species following rainfall events.

Complete metamorphosis with larval development extending over multiple years underground. Larvae are fossorial and feed on decaying organic matter and roots. Adults are short-lived and do not feed.

Adults are crepuscular or nocturnal and emerge during or after autumn rains. Males fly in search of females, which remain in burrows near the soil surface. Mating occurs in female burrows.

Larvae contribute to soil aeration and nutrient cycling through their fossorial feeding activities. Adults serve as a food source for vertebrate predators during their brief above-ground period.

No direct economic importance. Occasionally encountered by entomologists and naturalists during autumn fieldwork. The genus Pleocoma is of biogeographic interest due to its relictual distribution and phylogenetic position within Scarabaeoidea.

• Pleocoma hirticollis hirticollisNominate subspecies; distinguished by subtle morphological differences in setation and possibly male genitalia, requiring detailed examination.
• Other Pleocoma speciesOther species in the genus differ in pronotal setal patterns, antennal lamellae structure, and geographic distribution; precise identification requires reference to original descriptions and revisionary works.

• rain beetle
• scarab
• fossorial
• autumn emergence
• western North America

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• Catalogue of Life