Amongst bees, bumblebees have very long copulations when compared to honeybees and solitary bees. Up to three hours have been recorded for Bombus lapidarius, the Red-Tailed bumblebee, closer to half an hour for B. terrestris. I came across these paired Red-Tailed bumblebees (above) yesterday in the wildlife garden. The brightly coloured, smaller male was simply riding the female, and she bumbled along, feeding on knapweed and heavily flying between flower heads. Females would be expected to be very vulnerable to predators during this time, where they are also very obvious. Although they can actually fly, slowly and clumsily, their sting is immobilised by the male's genitalia. Illustrating this increased vulnerability, the couple of the same species below was squished on a busy pavement last summer.
Brown, M., & Baer, B. (2005). The evolutionary significance of long copulation duration
in bumble bees. Apidologie, 36 (2), 157-167 DOI: 10.1051/apido:2005008