California Native Plant Society
in collaboration with East Bay Municipal Utility District
Bee information
All writing from May Chen's posts
Yellow Faced Bumblebee
A Yellow-faced Bumble Bee, Bombus vosnesenskii (family Apidae) is collecting pollen from a flower of Bush Anemone, Carpenteria californica. There is so much pollen on those anthers on long filaments that all the bee has to do is run quickly through the stamens. The bee already has a sizable pollen load in her pollen baskets.
The pollen collecting apparatus in Apidae bees, which include honey bees and bumble bees, is commonly called a “pollen basket” or corbicula. This region is located on the tibia of the hind legs and consists of hairs surrounding a concave region. After the bee visits a flower, she begins to groom herself and brushes the pollen down toward her hind legs and packs the pollen into her pollen basket. A little nectar mixed with the pollen keeps it all together like putty, and the stiff hairs surrounding the pollen basket hold it in place. A honey bee can fly with a full pollen load that weighs as much as a third of her body weight.
Blacktailed Bumblebee
This bee is a worker Black-tailed Bumble Bees, Bombus melanopygus (family Apidae).Bombus melanopygus is a species of bumble bee native to western North America, widely distributed from the Pacific to the Rocky Mountains, and from Alaska to Baja California. The species is found in various habitats, including agricultural and urban areas. The bees feed on many types of plants, including manzanitas, Ceanothus, golden bushes, wild buckwheats, lupines, penstemons, rhododendrons, willows, sages, and clovers. They nest underground or aboveground in structures.
Western Leafcutter Bee
Leaf-cutter Bees, Megachile sp. (family Megachilidae) are stout-bodied, usually with pale hair on the thorax and stripes of white hairs on the abdomen. Females usually have a triangular abdomen with a pointed tip, and males’ faces are covered with dense, pale hair. Flight season is from May into September, with peak activity from June to August.
The males of this species use their “mittens" to cover the eyes of females while mating, presumably as blinders to calm them and increase receptivity.
Solitary females construct nests in tubular cavities, including hollow stems, tree holes, and abandoned beetle burrows in wood. Many use holes drilled into wood, straws, or other manufactured tunnels. Females cut pieces from leaves or flower petals for use in the construction of brood cells. Most Megachile females are generalists when foraging for pollen. Pollen is transported in dense scopae on the underside of the abdomen.
As she lands vertically on a flower, we get a view of her triangular, pointed abdomen. The males have a much more rounded abdomen.
Female Metallic Sweat Bee,
Lasioglossum (Dialictus) sp. (family Halictidae)
Lasioglossum species are found worldwide, and they constitute the largest bee genus. The subgenus Dialictus are the most likely to be seen in the U.S., with over 300 species of these tiny metallic bees. The majority of Lasioglossum are generalists. Because they are so abundant throughout the flowering season, the bees are often important pollinators. Their sheer numbers are enough to achieve excellent pollination of many wild flowers, especially of plants in the Asteraceae, which have shallow floral tubes that are easily accessed by these minute bees.
Lasioglossum are closely related to the genera Halictus and Agapostemon. These genera are commonly called “sweat bees” because of their attraction to human sweat, which they drink for its salt content. Lasioglossum are dusky black to brown slender bees with bands of hair on their abdomen. Female Sweat Bees (family Halictidae) carry pollen in the scopae on their entire hind legs and underside of their abdomen.
Lasioglossum exhibit a range of social behaviors; the genus includes solitary, communal, semi social, primitively eusocial, and even parasitic species. Almost all Lasioglossum in the U.S. nest in the ground. Generally these nests are built in the spring by fertilized females (called foundresses) that spent the winter in hibernation. In social species, the foundresses behave much like the queen Bumble Bees - they lay the first batch of eggs that develop into the first generation of female workers. The nest grows with each additional generation of bees. Later broods may consist of both males and females. They mate, and at the end of the season the fertilized females hibernate til the following spring, repeating the life cycle of the colony.
Texas Striped Sweat Bee-
Agapostemon texanus (family Halictidae)
A male Texas Striped Sweat Bee, Agapostemon texanus (family Halictidae) visits a Grindelia flowerhead.
In Greek, the genus name Agapostemon means "stamen loving", referring to the bee’s need to forage for pollen. The family Halictidae consists of small, non-aggressive bees with short tongues. They are called sweat bees because they are often attracted to human perspiration from which they obtain salts and water.
The Texas Striped Sweat Bee, Agapostemon texanus is most commonly found in the west coast of the United States. The species is easily recognized by its metallic green coloration. The females have an entire body that is brilliant blue-green, while the males have an abdomen that is brownish-black with yellow bands. The males (9-10 mm) are smaller than the females (11mm). Due to their short tongues, the Texas Striped Sweat Bees have a limited ability to access nectar from deep flowers. They are generalist foragers, visiting a wide range of flowers. Male Texas Striped Sweat Bees have a black-and-yellow striped abdomen, while the females are entirely bright green.
Female Agapostemon texanus are active May through October, while males are on wing from July through October. Two generations are produced per year. In the fall fertilized females overwinter in their nests while males typically die. In the spring the fertilized females emerge. They construct their underground nests in bare, loamy soil, lay their eggs in brood chambers and provision them with pollen before dying. In this first generation, the eggs hatch into mostly females as they develop from fertilized eggs. To fix the skewed sex ratio these females lay unfertilized haploid eggs that develop into males. During the summer months the male and female Texas Striped Sweat Bees mate, thus repeating the cycle.
Female Pacific Digger Bee
Female Pacific Digger Bee, Anthophora pacifica (family Apidae). Compared to earlier in the season, there are a lot more females than males now. See the yellow pollen load on this female’s hind leg? Male bees do not collect pollen; neither do they have the anatomy for the job.
As their name implies, the Digger Bees nest in the ground, sometimes in huge aggregations. These fast and noisy flyers buzz around flowers, appearing to “hop” from flower to flower while foraging. The chubby, furry Digger Bees resemble the bumble bees in many ways, but are a lot noisier. They are a fearless, rowdy lot - fun to watch but a challenge to photograph. Male digger bees of many species have white or yellow integuments on their faces. Females have shaggy hairs on their back legs, used to carry pollen. Female Anthophora are capable of buzz pollination - i.e. they vibrate their wing muscles to shake pollen from the anthers of some flowers. Digger bees are generalist pollinators that visit an impressively wide range of plants. They are exceptionally effective pollinators and play an important role in maintaining wildflower diversity, in part because their long tongues allow them to pollinate deep-throated and tubular blossoms inaccessible to other bees.
Female Pacific Digger Bees have long, shaggy hairs on their hind legs - they are the special pollen-collecting hairs collectively called scopae.
In contrast to the corbiculate bees such as bumble bees and honey bees with corbiculae ("pollen baskets") on their hind legs, the non-corbiculate bees such as this digger bee, do not wet and compress the pollen they have gathered, but instead take it away loosely held to the scopal hairs by electro-static attraction. Compared to pollen packed in corbiculae, pollen transported in the scopae are much easier to dislodge, resulting in more effective pollination and fertilization.