May 8, 2014
By Emily Hartop Out of the hundreds of bee species found in Los Angeles County, a single species gets most of our attention: Apis mellifera, the European honey bee. This species has a relationship with man that has existed for centuries. It is an exotic species that was introduced to North America. In addition to being widespread in the wild, they are widely used for pollination of commercial crops, as well as for honey — that sweet elixir of regurgitated nectar that is excellent in tea, cookies, breads, cakes, and all manner of other culinary delights. If you would like to know more about this species, we suggest the fun read "Sweetness and Light" by Hattie Ellis — what we'd like to focus on here are the many other bees with which you might not be as familiar. These are the bees that have been right here all along, our native bees of Los Angeles. Native bees are a diverse and fascinating group. Most of the species are solitary — meaning they build individual nests rather than living in colonies of thousands like the honey bee. Even the few of our native species that are social (like bumble bees and sweat bees) have colonies that rarely exceed a few dozen workers. One of the great things about native bees, apart from their fascinating diversity, is that they are not aggressive stingers. Ironically, the bees that have the cutest, fuzziest image (the aforementioned honey bees and bumble bees), are the most prone to give you a nasty sting. Native bees are mainly attracted, obviously enough, to native plants, from which they gather pollen for their offspring. Most of the solitary species of native bee tend to specialize on a specific plant or group of plants for pollen, while some of the social species are generalists that will take advantage of more diverse resources. All types of bees will visit virtually any flower for nectar. Bees that take advantage of more diverse resources are better adapted to make use of the wide range of resources that may be available in urban environments.
Photo by Kelsey Bailey. The beautiful bee above is a male bee in the genus Agapostemon. In the family Halictidae, they are also known as Metallic Sweat Bees. Though they are part of this family, named because of their attraction to sweat, this particular genus does not exhibit this trait. This specimen is easily distinguished as a male bee — females of this species are uniformly metallic, while males have a more typical "beelike" striped abdomen. Most Agapostemon are solitary, digging a deep vertical burrow in sloping soil or bank. When to look for them: Summer to fall Where to look for them: On composite "daisy-like" flowers
Photo by Kelsey Bailey. Pictured above is perhaps the most endearing genus of bees, Bombus: the bumble bees. This particular specimen is the one and only bumble bee that has been caught in a BioSCAN trap (Site #1, NHMLA Nature Garden). There are 26 species of bumble bees in California and some have been in serious decline since the 1990s due to commercial keeping of bumble bees, habitat loss, pollution, and climate change. Bumble bees are generalists with long tongues that can obtain nectar from even very deep flowers. They are social bees that live in colonies of up to 1,000 individuals, although most colonies have under 50 bees. These colonies, unlike honey bee colonies, do not provision for overwintering. Instead, the colony dies off in the fall and the queen overwinters alone — emerging in spring to start up a new colony. Bumble bees are better pollinators than honey bees for crops like tomatoes, cranberries, raspberries, blueberries, and field beans. This is partly due to the fact that some flowers only release pollen when the anthers are vibrated at certain frequencies — the "buzz" of a bumble bee accomplishes this! When to look for them: Early spring to late fall Where to look for them: Flowers with tubular shapes
Photo by Kelsey Bailey. Our next bee is a specimen from the genus Andrena — a Miner Bee. Before we get into the details on this genus, we want to show you how much care and love go into specimen processing for bees. Below, you see my esteemed colleague and entomological other half, Lisa Gonzalez, carefully drying a bee (look at the intense expression — this is serious!). Using a paintbrush (close up, second photo below), Lisa carefully fluffs up the hairs on each bee as she uses a blow dryer to dry them. Without this extra effort, the fuzz on bees would dry matted and stuck together. So all the fluffy bees in these blog photos are thanks to Lisa's delicate handiwork! [caption id="attachment_378" align="alignnone" width="1406"]Photo by Phyllis Sun.[/caption] [caption id="attachment_380" align="alignnone" width="1504"]Photo by Phyllis Sun.[/caption] Andrena is associated with willow, and emerges in large numbers in spring when willow blooms. This makes perfect sense to us — we found over 100 bees in a single spring sample from right near the L.A. River, where there is plenty of willow growing! These bees are mostly solitary, but nests can be clustered together in aggregations in sandy soil or near shrubs. When to look for them: March-September Where to look for them: Nearly any sort of flower — including wind-pollinated species like willows
Photo by Kelsey Bailey. This next bee is a large leaf-cutter bee from genus Megachile. Leaf cutters use their mandibles (mouthparts) to cut leaves or flowers of plants and use them to form nest cells. This genus includes both specialist and generalist species, including M. rotundata which specializes on alfalfa and is an introduced species critical to commercial pollination of that crop. These bees are cavity nesters, and will make use of bee hotels — they will line cells with the pieces of leaves they cut. This group also includes some species that use resin and mud to build above ground nests and some ground dwellers — most are opportunists that take advantage of their surroundings. An interesting feature of Megachile is that the scopa, which is a group of hairs that collect pollen, is on the underside of the abdomen, whereas most bees have this adaptation on their legs. One of the scientists working at the Museum, Anna Holden, works on Megachile from the La Brea Tarpits. A National Geographic article featured her work, you can find that article here. When to look for them: Summer Where to look for them: Many flowers, but especially in the pea family (Fabaceae) A related genus of bees, the small leaf-cutter bees, genus Osmia, win the award for the cutest bees! These small, stout bees have an abdominal scopa like their larger cousins the Megachile. They often have a metallic green or blue sheen, and are efficient pollinators of a number of fruit trees. 250 female bees of this genus can out-pollinate tens of thousands of honey bees! We had to mention them here so that we could share this amazing video of an Osmia using an abandoned snail shell for a nest, or how about this beautiful use of flower petals? When to look for them: Spring to summer Where to look for them: Mostly perennial shrubs and trees, and Phacelia If you'd like to attract native bees to your own yard, the Xerces Society webpage is a great resource. Additionally, bee hotels can be made or purchased in a variety of forms to help your garden space become a nesting place for solitary species. There are many resources for different types on the internet, but you can start here. For more information and help with indentifying native bees, we recommend the Field Guide to the Common Bees of California by Gretchen Lebuhn.
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