Photo: Hibiscus Turret Bee, Judy Gallagher
Judy Gallagher is an ASNV board member and a regular surveyor of local wildlife who also captures photos of what she sees, in particular the less common species.
Hibiscus Turret Bee (and a weevil) in Swamp Mallow, Judy Gallagher
Bumble Bees are tricky to identify, and I'm rarely sure that I have correctly determined the species for my photos. So, when I first saw large bees on Swamp Mallow, I thought they were Common Eastern Bumble Bees. I submitted my pictures to iNaturalist and was surprised to discover that the bees were Hibiscus Turret Bees, a specialist bee species that collects pollen from flowers in the Hibiscus family, including Swamp Mallow.
The Hibiscus Turret Bee does resemble a small bumble bee, but instead of having pollen baskets on its legs, it has dense thick black hairs on its legs for collecting pollen. The Hibiscus Turret Bee's head and thorax are larger relative to body size than a bumble bee's.
Hibiscus Turret Bee collecting water, Judy Gallagher
Hibiscus Turret Bees are solitary, ground-nesting bees, but they frequently nest close to other bees of the same species. They dig their nests in hard-packed dirt areas close to water sources. To make nest excavation easier, bees alight on the water’s surface to collect water to moisten the soil.
Hibiscus Turret Bee removing wet soil from nest , Judy Gallagher
As you can see in the picture above, the entrance to the nest is surrounded by a turret, which looks like a mud chimney. Each nest contains several chambers lined with a waterproof substance that the bee excretes.
Hibiscus Turret Bee with pollen, Judy Gallagher
The Hibiscus Turret Bee female puts a ball of pollen and nectar in each chamber and lays an egg on it. When the egg hatches, the larva eats pollen and nectar until it is ready to pupate. The larva then deposits a layer of fecal material covering the entire inside of the cell, and then covers itself in a cocoon. It overwinters this way, and emerges as an adult to coincide with the blooming of plants such as Swamp Mallow.
Hibiscus Turret Bee in Hibiscus , Judy Gallagher
Males sit inside Hibiscus flowers, waiting for females. Males defend their flowers aggressively, and studies show that this behavior contributes more to hibiscus pollination than female visitation to flowers. One study showed that males made only 5% of pollen visits to Hibiscus flowers, but contributed over 20% of the pollen grains deposited on other Hibiscus flowers. Interestingly, the male Hibiscus Turret Bee also will get nectar and pollen from plants besides Hibiscus, but the female pretty much only goes to plants in the Hibiscus family, and occasionally Morning Glories.
Green Metallic Sweat Bee and Hibiscus pollen, Judy Gallagher
Hibiscus pollen grains are relatively large, so aren't easily carried by small bees. Here's what happened when a small green metallic sweat bee tried to collect Hibiscus pollen. The pollen was heavy enough to flip the bee on its back. The bee righted itself with some difficulty, shook off most of the pollen, and took off to find pollen more suitable for its size.
Hibiscus Turret Bees, like other specialist bees, are vulnerable to climate change and habitat destruction. They rely on plants in the Hibiscus family as their primary food source. So, the next time you see a Swamp Mallow bloom, take a peek inside the blossom to see if you can find this gorgeous bee.
View more of Judy’s Observations from Meadowood articles here.