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With summer here, gardens are buzzing with pollinators—and not only the honey bees. The European honey bee is just one of more than 20,000 bee species worldwide. Honey bees were brought to America by settlers, only reaching the West Coast in the 1860s. Before that wild, unmanaged bees provided most of the pollination of wildflowers and crops. Native bees are still the most important pollinators of wild plants, helping to maintain ecosystem diversity. Bees also help feed people: one out of every three bites of food we eat needs a pollinator to grow. Native bees are very important for pollinating crops, and they are often better at it than honey bees because they spend more time on each flower, which means they move more pollen.
Most bee diversity is concentrated in Mediterranean environments, however, the Pacific Northwest also hosts numerous species. Most bees live alone, which means they don’t live in large groups with different people doing different jobs, like honey bees do. Social bumble bees build their nests in holes in the ground, but wild bees that live alone either dig holes in the ground or find hollow stems to live in. Because it rains a lot in the Pacific Northwest, the second option is a much better choice for nesting because plant stems are less likely to get wet than soil. Most native bees live alone, so they don’t have to protect a hive. This makes them much less likely to sting than honey bees. In fact, you really have to get a native bee mad to provoke it into stinging you.
Unfortunately, both native bees and honey bees are currently declining due to a number of threats. Habitat loss is one of the major drivers of biodiversity loss worldwide. Even remnant habitat fragments are losing value due to the spread of non-native invasive plants. The invasives compete with the native species most wild bees rely on for pollen and nectar. Disease spread is another major issue facing bee populations. Managed bees, like bumble bees used for tomato pollination, spread disease to native bumble bees. Many bumble bee species that were once widespread have disappeared throughout most of their range. Before, the western bumble bee (Bombus occidentalis) was the most common species west of the Mississippi. These days, you only see them once in a while. Franklin’s bumble bee (Bombus franklinii), which has a smaller range, hasn’t been seen or heard from since 2006, even though its old home range in Southern Oregon has been searched extensively.
You can help with bee conservation by planting flowering plants in your yard for year-round, continuous bloom. Pay attention to native species because ornamental plants, even if they look nice, don’t always produce the pollen and nectar that bees need. Bees also need nest sites, either undisturbed bare soil or pithy-stemmed plants (like raspberries). See the “Native Plants for Native Bees” for some recommendations. You can find more plant lists for pollinators in your area, as well as nurseries and other helpful information, at www. xerces. org/pollinators-pacific-northwest-region.
Washington is home to an impressive diversity of bee species. Among the most frequently encountered are black bees which come in a variety of shapes and sizes. Here are some of the common black bee species found buzzing around the state of Washington
Large Carpenter Bees
The large carpenter bee (Xylocopa virginica) is one of the most recognizable black bees in Washington. As their name suggests, these chunky, shiny black bees bore holes in wood to make their nests. With bodies up to 1 inch long, carpenter bees can be mistaken for bumblebees. However, carpenter bees are solitary rather than living in colonies. Their nests house just one female bee and her young.
Carpenter bees are important pollinators of flowers crops, and trees. Though the males can be aggressive in defending territory their sting is mild compared to other bees.
Small Carpenter Bees
The small carpenter bee (Ceratina spp.) is all black with a greenish or bluish metallic sheen. At just 1/4 to 1/2 inch long, these bees are much smaller than the large carpenter bee. Rather than burrowing into wood, small carpenter bees nest in hollow plant stems.
These gentle bees are valuable native pollinators Their small size allows them to pollinate flowers missed by larger bees
Digger Bees
Washington is home to around 30 species of digger bees in the Anthophorini tribe. As their name suggests, these plump, fuzzy, black bees dig underground burrows. Several females may nest in the same area, giving them a social-but-solitary lifestyle.
Digger bees are docile despite their size. They rarely sting unless directly threatened. These important pollinators frequent crops as well as wildflowers.
Masked Bees
Tiny masked bees (Hylaeus spp.) are all solid black except for yellow/white facial markings. Their black, hairless bodies and lack of pollen baskets cause them to resemble wasps. Unlike wasps, masked bees feed strictly on pollen and nectar.
Though just 1/4 inch long, these native bees are found on every continent except Antarctica. In Washington, look for them pollinating flowers near their nests in hollow twigs.
Miner Bees
Miner bees (Andrena spp.) are plump, hairy, and black with bright yellow fuzz on the thorax. The females dig long underground burrows. Their nest entrances are surrounded by little piles of excavated soil.
These important early spring pollinators resemble bumblebees but are much more solitary. Miner bees have a mild sting but rarely bother humans.
The variety of black bee species in Washington fills diverse ecological roles as pollinators. Getting to know them can make identifying these beneficial insects easier.
Major Bee Groups in the Pacific Northwest
People who want to help with conservation may find it useful to have some knowledge about the things they are trying to protect. Here are profiles of some of the major bee groups in our region. Next time you’re out in your garden, see how many of these groups you can identify.
BUMBLE BEES (BOMBUS)
Life History: Bumble bees are some of the most important pollinators. From early spring, when the queens come out to find food for their new colonies, until late fall, they are busy. Bumble bees can buzz pollinate, which means they can vibrate a flower at a frequency that makes pollen inside the flower explode on the bee. Bees that can’t buzz pollinate are ineffective pollinators of plants that require it, such as tomatoes. Also, bumble bees are generalists, which means they don’t just stick to a few types of plants. They visit a lot of different kinds of plants. They also have large ranges, enabling them to pollinate plants over great distances. In many ecosystems, bumble bees are keystone species, which means that many other species depend on them.
Description: Bumble bees are easy to identify, with their large, fuzzy bodies and iconic black and yellow banding. Some species of bumble bee have white or orange markings as well. Like honey bees, bumble bees carry moistened balls of pollen on their hind legs.
In the Pacific Northwest, you can often see the fuzzy-horned bumble bee (Bombus mixtus), the yellow-faced bumble bee (Bombus vosnesenskii), and the California bumble bee (Bombus californica).
MASON BEES (OSMIA)
Life History: Mason bees get their name from the way they build their nests out of mud to make cell divisions. Providing access to mud can help support populations of wild mason bees. Mason bees are solitary, and they make their nests in naturally occurring, above-ground cavities. They mate in spring, and then the female bees collects nectar and pollen provisions for their nests. Each female then finds a hole or tunnel in which to create a compartmentalized nest for her eggs. With the eggs fully provisioned, the female then plugs up the entrance. The larvae hatch, feed, hibernate through winter in cocoons, and emerge in spring to start the cycle afresh. Mason bees are very efficient pollinators and are active from spring through late summer. Commercial mason bees are sold to help with pollination, but they may hurt wild mason bees that live in the area (see “Downside to the Mason Bee Trade” for more information). ”.
Description: Mason bees often have exoskeletons with metallic coloration ranging from green to teal. They have a narrower body than leafcutter bees, though they also carry pollen under their abdomen.
Common species in the Pacific Northwest: blue orchard mason, Osmia lignaria; Osmia brevis; Osmia occidentalis; Osmia pusilla.
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More and more people are keeping mason bees for pollination in farms and gardens because they are easy to find. There are, however, species that have spread outside of their native ranges because of the trade in mason bees. This can make native species less successful. Some mason bees, like the blue orchard mason bee (Osmia lignaria), have wide ranges, but different species’ populations have developed ways to survive in their own areas. The Xerces Society for Invertebrate Conservation suggests first making a habitat that supports wild bee populations in the area by giving them lots of flowers to pollinate all year. If you do decide to buy mason bees, you should get them from your own area and never use species that aren’t native to your area, like Osmia rufa, which is native to Europe.
Even though more research needs to be done on the possible bad effects of non-native mason bees, taking precautions will help reduce the number of problems that might happen in the future. If you make mason bee nests out of things like bee hotels (straws with holes drilled in them), keep in mind that these can get parasites inside them over time. Every three to five years, nests should be cleaned or burned so that diseases and parasites don’t build up and hurt wild mason bee populations.
SWEAT BEES (LASIOGLOSSUM & HALICTUS)
Life History: Sweat bees got their name because some species collect salt from animal sweat, including from humans. Although sweat bees are small and dark, they are not the typical black and yellow color of bees. For these reasons, sweat bees are often confused with flies. They spread pollen by climbing deep into flowers and staying there for a long time to drink nectar and gather pollen. They’re kind of social, with mothers and daughters living together, but they don’t share work or stop each other from having babies (short for “queen”). They are often one of the most common bee species in urban and agricultural environments.
Description: Sweat bees are usually black or dark metallic grey. Some species have pale hairy strips on their abdomen. They carry dry pollen on their hind legs.
In the Pacific Northwest, you can find the small sweat bee (Halictus tripartitus), the medium sweat bee (Halictus ligatus), and the tiny sweat bee (Lasioglossum species).
MINING BEES (ANDRENA)
Life History: Mining bees excavate nests underground, hence the common name. Not only do bumble bees pollinate blueberries, but these birds do too. They often build their nests at the base of blueberry plants. (One native species, Andrena astragali, is only found in Australia and is a specialist pollinator of the death camas (Zigadenus species), which is why it is called the death camas bee. ) They also have been known to nest in lawns. Mining bees live alone, and each female builds a few nests during her short life, which is usually only four to eight weeks. Each nest has about five cells, or chambers, in the ground that are filled with enough pollen for one bee larvae. One egg is laid by a female bee in each cell, which is then sealed with mud. The female bee never sees her young. After an egg hatches, the larva consumes all the pollen, then metamorphoses into an adult bee. Winter and the rest of the year, it stays underground in diapause (a state of paused development) until the right seasonal cues (like temperature and moisture) tell it it’s time to come out to reproduce and pollinate.
Description: Mining bees often have fuzzy orange or blond thoraxes (mid sections) and dark abdomens with light stripes. They carry their pollen dry on their hind legs, which makes them look like they are wearing chaps.
Common species in the Pacific Northwest: Death camas bee, Andrena astragali; snowy adrena, Andrena nivalis; Andrena evoluta.
LEAFCUTTER BEES (MEGACHILE)
Leafcutter bees get their name from the fact that they cut up leaves or petals to make cell divisions in their nests. To help them cut up plant parts, leafcutter bees have big mandibles, which are cutting tools that are kept in their mouths. Leafcutter bees nest above-ground in holes in wood. Because there isn’t much room for their legs, they carry the pollen under their stomachs instead. This bee type is also known as “hairy-belly bees,” which comes from the special hairs, or “scopa,” on the underside of its body. Leafcutter bees often lift their bellies when they eat flowers so that their bellies don’t wipe the pollen off the flower. This posture distinguishes them from other bee species. Leafcutters can hurt some garden plants on the surface, but they make up for it by being very useful pollinators in the summer. (If they are going after a valuable rose or other plant, you can cover it with row cover cloth until the bees find something else to eat.) ).
Description: Leafcutter bees are often more squat-looking than other bee species. They carry their pollen under their abdomens, which are usually black, with pale bands of hair.
Common species in the Pacific Northwest: western leafcutter bee, Megachile perihirta; silver-tailed petal-cutter beer, Megachile montivaga.
CUCKOO BEES (SPHECODES, NOMADA, TRIEPEOLUS, COELIOXYS)
Life History: Cuckoo bees get their name from the cuckoo bird because they are also parasitic. Instead of building their own nests, cuckoo bees lay their eggs in the nests of other bees. When the cuckoo bee larvae hatch, they can move and find the larvae of their host to eat. Because cuckoo bees don’t have to gather pollen to feed their young in the nest, they tend to look less hairy. Cuckoo bees depend on their host species for food, so if host populations go down, cuckoo bees will probably go down too.
Description: Cuckoo bees are often red or yellow, and sometimes have white markings. They are often nearly hairless, and so can have a wasp-like appearance.
Common species in the Pacific Northwest: concave cuckoo bee, Triepeolus concavus.
Hillary Sardiñas is the former Pacific Coast Pollinator Specialist for the Xerces Society for Invertebrate Conservation. She now works as a biologist for the Alameda County Resource Conservation District. For questions about this article or the Xerces Pollinator Program, email pollinators@xerces. org.
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How to identify Africanized bees
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