Apidae > Ptilothrix > Ptilothrix bombiformis
Hibiscus turret bees (Ptilothrix bombiformis) does a great job mimicking bumble bees in appearance, but it couldn’t be more different when it comes to nesting. This solitary bee digs thrives in compacted soils near wetlands such as levees, walking paths, and parking lots. Remarkably, females skate on top of the water like a water strider in order to gather water to moisten the compacted nesting soil. P. bombiformis is found near large-flowered Malvacaeae, such as the native swamp rose mallow Hibiscus moschuetos and ornamental rose-of-sharon Hibiscus in gardens.
Phenology
One generation per year, active in July and August.
Range
Southeast and mid-Atlantic latitudes, from Virginia north to New York City.
Appearance
Size > honey bee
Females most resemble bumble bees in size and coloration, with an all pale thorax, with short, dense,. even hairs, and a shiny black abdomen with dark amber hairs on T1. Head is very round with yellowish hairs on face. Scopae on hind legs are thick and brush-like.
Males very similar to females but without hind scopae.
Similar species
- Anthophora bomboides has pale hairs on the second segment of the abdomen and male has pale clypeus.
- Bombus impatiens and Bombus griseocollis are similar, but have a more elongate (less round) head. Bombus workers have corbicula, not scopae. Bombus also typically have slower, more laboring flight pattern.
Nesting
Typically found nesting suburban and urban areas, as well as on hard-packed roads and levees cutting through wetlands, especially coastal salt marshes. Females construct nests underground in flat, highly compacted soils. Nesting sites are typically located near a source of water, so that females are able to moisten the nesting substrate and make it easier to dig. As females excavate, they leave small pellets of moistened soil outside the nest entrance. Entrances are perfectly round and typically turreted, which is where this species gets its name. Many females may nest in the same area, forming a small aggregation.
Foraging
Pollen specialist of large-flowered Malvacaeae, including swamp rose mallow Hibiscus moschuetos, but also ornamental rose-of-sharon Hibiscus and okra Abelmoschus. Recorded nectaring on some Asteraceae like coneflower Echinacea, blanket-flower Gaillardia, and cosmos Cosmos. Also a frequent visitor to morning glories (Convolvulus), presumably as a nectar source.
Natural Enemies
No parasites of P. bombiformis are known.
References
Rust, R.W. 1980. The biology of Ptilothrix bombiformis (Hymenoptera: Anthophoridae). J. Kans. Ent. Soc. 53: 427-436.
Page last updated:
January 17, 2023