It’s Pollinator Week!

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Pollinators in the form of bees, birds, butterflies, bats and beetles provide vital but often invisible services, from supporting terrestrial wildlife and plant communities, to supporting healthy watersheds.

Bevy of Bees

The top view of a male Anthophora occidentalis bee
This male Anthophora occidentalis was collected in June of 2012 from Badlands National Park, South Dakota. Photo by Sam Droege, USGS. (Public domain.)

Bees are nearly ubiquitous, occurring on every continent except Antarctica. Wherever there are insect-pollinated flowering plants — forest, farms, cities and wildlands — there are bees. And just because you don’t see plants blooming, does not mean that there are no bees around.

There are nearly 20,000 known bee species in the world, and 4,000 of them are native to the United States. From the tiny and solitary Perdita minima, known as the world’s smallest bee, to the large carpenter bee, to the brilliant blue of the mason bee; native bees come in a variety of shapes, sizes and colors.  And all these bees have jobs, as pollinators.

Providing Ecosystem Services

Native bees pollinate plants like cherries, blueberries and cranberries, and were here long before European honeybees were brought here by settlers.

Honeybees, of course, are well known for pollinating almond and lemon trees, okra, papaya and watermelon plants. But native bees are estimated to pollinate 80 percent of flowering plants around the world. And none of them sting – really!

According to the USDA, bees of all sorts pollinate approximately 75 percent of the fruits, nuts and vegetables grown in the United States, and one out of every four bites of food people take is courtesy of bee pollination. In sum, bee pollination is responsible for more than $15 billion in increased crop value each year.

Bees are vegetarians who descended from wasps about 125 million years ago when the first flowering plants evolved. Some wasps switched from hunting prey to gathering pollen, evolving to become bees. Bees feed on both nectar and pollen – the nectar is for energy, and the pollen provides protein and other nutrients. Most pollen is used by bees as larvae food, but bees also transfer it from plant-to-plant providing the pollination services needed by plants and nature as a whole.

Home Sweet Home

Most native bees build nests and provide food for their offspring, but about 20-25 percent have gone the way of the cuckoo birds, laying their eggs in the nests of others. Aside from the “cuckoo” bees, all bees build nests, and stock them with pollen and nectar before laying their eggs. Some, like the sweat bee, build nests underground while others choose hollow stems or holes in trees, like the leafcutter bee.

Got Bees? USGS Does

The USGS Native Bee Inventory and Monitoring Program designs and develops large- and small-scale surveys for native bees. As part of the program they also provide the first-ever comprehensive identification tools and keys for North American native bee species. Established in 2004, the program has made advances in bee monitoring, and developed and tested survey techniques that were incorporated into the bee manual, “The Very Handy Manual: How to Catch and Identify Bees and Manage a Collection.”

This photo is a head on image of a Bombus griseocollis queen bee.
A Bombus griseocollis queen. Photo by Sam Droege, USGS. (Public domain.)

Program scientists have also devised a technique for collecting and processing native bee specimens for the inventory, as well as having developed an easy-to-use permanent monitoring technique was deployed nationally in 2014. The program also manages the world’s largest international listserv of bee monitoring and identification.

USGS and its partners have conducted native bee inventories at more than 100 national parks, wildlife refuges and forests; and nearly 1,000 super-high resolution public domain images of bees and wasps are available online. The program’s native bee database of approximately 250,000 collection records of bees and wasps rivals that of the largest museums. Records can be viewed at the Discoverlife and Encyclopedia of Life websites. Even with all that is being learned about native bees, native bee researchers still face challenges.

Population Declines: Beyond Honey Bees

Colony collapse disorder, the cause of which is unknown, affects only European honeybees and has been recorded across the county. The primary symptom of the disorder is having no or low numbers of adult honeybees present in a hive; no dead honeybees are present, but a queen is. Immature bees will be present and honey will still be in the hive.

Fortunately, colony collapse disorder does not affect native bees, though some native bees and other pollinators are also experiencing population declines and range reductions. Native bee species are being affected by at least some of the same factors affecting honeybees such as habitat loss, fragmentation and disease, as well as the use of pesticides.

What can you do for native bees?

To increase or improve habitat for native bees, plant a diversity of pollen and nectar sources native to your area that bloom at various times during the year. Native plants and native pollinators have mutually adapted over the millennia. Many native bee species are pollen specialists and need to provide their young with pollen from native plants, so providing native plants will increase the diverse community of native bee species.

If possible, avoid use of pesticides and provide a source of pesticide-free water, and mud, which is used as a nesting material by some bee species. You can also provide nesting habitat for native bees by rototilling a bare spot in the lawn or garden for soil-nesting bees, leaving standing dead trees, which will provide housing for native bees, or building a bee house. For more tips, listen to our podcast, Bees are Not Optional.