What are Bees Busy Doing in Our Watershed?

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Kelley Ahlers is one of our AmeriCorps staff here at SYRCL. Before joining us, she  worked in an insect ecology research lab at The Ohio State University where she studied solitary bees native to central Ohio. In this piece, Kelley introduces us to some of the bees here in the Yuba watershed after explaining the important role they play in our ecosystem.

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What are bees busy doing?

You may be familiar with non-native European honeybees (Apis melifera) because they are used commercially to produce honey and pollinate crops. Unlike honeybees, native bees are wild and mostly solitary.

Bees play a crucial role in the plant reproductive process through pollination – movement of pollen grains from anther to stigma. Pollination can occur abiotically through wind or water, or through living pollen vectors like insects, birds, and even mammals. Insects like butterflies, moths, beetles, and flies contribute to pollination, but bees do the heaviest lifting. 

It is estimated that native bees pollinate 80% of the world’s flowering plants. Through pollination, bees contribute to healthy, diverse, and productive plant communities. 

A bee spotted in Nevada City near the post office (Photo: SYRCL staff)
Bees found in a meadow (Photo: SYRCL staff)

California is home to 1600 species of native bees. Below are some of the bees you may see around the Yuba River watershed.

Blue Orchard Bee (Osmia lignaria)

Blue orchard bees are dark metallic blue. Since these are solitary bees, each individual female tends to her own brood and males only play a small role in reproduction. When they emerge in early spring, they mate and begin building nests. They are mason bees, so they use mud or clay to build their nests. Females build nests in holes with separate chambers for each egg. Every chamber has a ball of pollen and nectar which will nourish the bee larvae until they emerge the following spring. Their pollen carrying structures are called scopae – dense collections of branched hairs on the underside of their abdomens. These bees pollinate fruit trees so efficiently that farmers try to attract them by providing them with hollow tubes to nest in.

Blue Orchard Bee (Photo: USFS)

Yellow-faced Bumblebee (Bombus vosnesenskii)

Yellow-faced Bumblebee (Photo: iNaturalist user ltbloomer)

Yellow-faced bumblebees are one of the most common bee species on the west coast. They have (you guessed it) yellow faces and a single yellow stripe on their abdomens. Generally, bumblebees have large and furry-looking bodies with pollen carrying structures on their back legs. 

Bumblebees are social and have an annual colony cycle. A colony begins when the overwintering queen emerges in the spring and finds a nest to lay her egg brood. Bumblebees tend to nest in underground rodent burrows. The queen will forage for nectar and pollen for her young, who will become workers when they hatch. The colony grows for a year until a new generation of queens hatches, venture off to new nests, and hibernate for the winter.

Eight-toothed Cuckoo Leaf-cutter Bee (Coelioxys octodentatus)

Cuckoo bees are cleptoparasitic, meaning they lay eggs in the nests of other bees. They belong to the family Megachilidae and they tend to parasitize related bees. They lack pollen carrying structures because their larvae consume pollen collected by the host. They are black with white stripes and they have cone-shaped bodies. When their egg hatches in the host’s nest, the parasite larva kills the host larva.


Eight-toothed Cuckoo Leaf-cutter bee (Photo: iNaturalist)

How to Help Our Native Bees?

Unfortunately, bee populations are threatened by climate change, habitat loss, pesticides, and pollution. If you would like to help, consider planting a pollinator garden with native flowers. Try to plant a variety of flowers whose blooming periods span from early spring to late summer so that the bees always have a food source. You can also help by supporting SYRCL’s conservation and restoration efforts! Check out our meadow restoration projects for more information. 

If you are interested in learning more about bees, check out these readings by clicking on the links below:

We also recommend watching one of our Wild & Scenic Film Festival short films about the impact bees are making in one community titled Detroit Hives.

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