Backyard bees: multi-year fidelity to a sleeping roost site by male Melissodes bimaculatus (Lepeletier) (Hymenoptera: Apidae) and co-roosting by parasitic Triepeolus lunatus (Say) (Hymenoptera: Apidae) in southeastern Louisiana

Little is known about the formation, persistence, or dissolution of sleeping clusters of male bees at night roosts. We report multi-year fidelity of male Melissodes bimaculatus (Lepeletier 1825) (Hymenoptera: Apidae) sleeping clusters to a single backyard patch of irises (Iridaceae: Iris) in Baton Rouge, Louisiana. In addition, during two consecutive years, individuals (at least one male and one female) of Triepeolus lunatus (Say 1824) (Hymenoptera: Apidae) co-roosted with the male M. bimaculatus. Individual bees settled near other bees for their nocturnal rest or nighttime inactivity periods. They also appeared to sometimes bias their specific choices for roosting positions toward plant parts against which or near which their bodies were somewhat camouflaged. Thermoregulation is an unlikely ultimate evolutionary explanation for aggregated sleeping behavior in these particular bees, but protection from predators through safety in numbers and opportunities to glean information from roost mates remain as plausible adaptive explanations. We propose an extension of the Information Center Hypothesis for co-roosting by parasitic bees with their host species.