Native Bees

Welcome to the Amazing World of Native Bees

Did you know there are nearly 4,000 different native bees identified in North America with new ones being discovered every year?  Little is known about most of these bees except for a few species with significant economic importance for pollinating orchards, berries and field crops.  However, one obvious contribution by all bees to the ecology of the planet is pollinating a wide variety of plants that not only benefit the plants themselves but sustains organisms along the food chain including humans. salvia w grey bee cropped

The presence of native bees increase crop yields in vegetable gardens, berry patches, and fruit orchards.

The well known honeybee is not among the list of North American native bees but first arrived with European colonists.   Honeybees differ greatly  from the native bees as they are the only bees to have a highly functional communal society and produce honey.  By contrast, most native bees may nest close to each other but each female is considered solitary in that she builds her nest and provisions her eggs with pollen and nectar without help. Some natives bees share short term responsibility in a communal nest such as the bumble bee. Click here for more information on the Bumble Bee life cycle.

Today, native bees face many challenges for survival through loss of habitat, pesticides, herbicides, exotic diseases and predators, and disappearance of native flower populations. Overall, native bee populations are on the decline. Along the Wasatch Front in Utah, urbanization is fast claiming open lands in the lower valleys and native habitats in the foothills and mountain valleys. With urbanization comes changes in vegetation, greater pesticide and herbicide use, and dramatically reduced potential nesting sites.

What Can You Do?

aschlepius w green beeThe good news is that you can attract and support native bees in your landscape and garden and reap the benefits of abundant food crops as well as the entertainment value of watching them.  Native bees will typically stay close to their nest to forage so three things are vitally important for their survival—provide food, keep them safe from toxins, and provide nesting opportunities.

Grow flowers beneficial to bees.  Select plants for their flowering time so nectar and pollen are available throughout the growing season.  The more bee friendly flowers you have in your yard over the entire growing season, the more likely they will be attracted. A list of bee beneficial plants for Northern Utah can be downloaded here.

Eliminate or minimize the use of pesticides, herbicides, and chemical fertilizers.  These chemicals can harm more beneficial insects than the target species.  If pesticides, herbicides, and chemical fertilizers have to be used, even if labeled organic, educate yourself on the active ingredients, read directions, and apply with care.

Provide nest habitat and artificial nest sites.   Watch for bees on your flowers and you may  start to notice a variety of sizes, shapes and colors of bees.  Each species have their own nesting and rearing requirements.  They can generally be broken into 1) those that nest above ground in dead wood with beetle tunnels, hollow twigs, or crevices and 2) those that nest in tunnels deep in the soil.  Bumble bees will nest on or slightly below ground not in tunnels.  Approximately 30% of native bee species nest in wood or twigs and 70% nest in the soil.  The following gives you more information on these two groups of bees and how you can help them find a home in your yard.

Ground Nesting Bees

Ground nesting native bees include the squash bee that pollinates its namesake, squash.Click here for more information on squash bees. Ground nesting bees will tunnel deep into the soil and build their nests.  The tunnel built by the female and is often lined with secretions that holds the soil in place.  Sometimes she builds a neat rim at the surface.  She comes and goes, building compartments, or brood cells, then laying an egg in each with a ball of pollen and nectar to sustain the larvae until it emerges the following year.

If you see bee activity near holes in your garden or yard, do not disturb the soil.  After the activity has stopped and the entrance is sealed with materials  that the female places there, the surface may be disturbed including tilling your garden.  The nest will be below the surface at least 18 inches and the emerging adults will make their way to the surface in the loosened soil.

One way to help these ground dwellers is to not use weed cloth in your planting beds.  Besides eliminating bee habitat, weed cloth adversely affects plant growth, particularly water-wise plants,  because it will keep the roots zone too dry and cool.  Rather, use mulch and leave a patch of soil uncovered for the bees.

Wood Nesting Bees

This group includes bees that are important pollinators for fruit trees, berries, sunflowers, and other crops.  Like the ground nesters, the females will occupy a tunnel creating partitions to hold a single egg provisioned with a ball of pollen and nectar.  The tunnel entrance is then plugged to protect her brood until they emerge the following year.  Depending on the species, a variety of materials including mud, leaf pieces, chewed up petals, and tiny pebbles are used to partition and seal the nest.  The type of material gives a clue as to who is its occupant.

The removal of dead trees and the prevalence of lawns in urban settings has bee house samplereduced the habitat of this group of bees and has limited its population.  However, they will successfully use artificial nests as shown through research done for bee management in commercial crops.  A variety of materials can be used to build a nest such as drilled wood blocks or logs, bundles of straws, twigs, or bamboo.  However, to have a successful nest, certain requirements need to be met for hole size, length and spacing, nest location, and maintenance.    Several sources of native bee nest houses for sale can be found on the internet.   For do-it-yourselfers, click here to make your own bee house for the Blue Mason Orchard Bee.

Similar to bird houses, different sizes and depths of holes will attract certain bees to nest. The bees most likely to be attracted to nest in the artificial nest boxes you buy or are home-made are of the Family Megachilidae which include Mason Bees, Leafcutter Bees, Wool Carder Bees.  They have a wide head and strong jaws needed to gather nesting materials.  The females perform the important task of pollination as they gather pollen to provision their nest.  They carry pollen on the fur of their abdomen rather than on the long hairs of their hind legs like many other bees.  They are typically tolerant of human activity and are not likely to sting.

Each species will emerge over a period of a couple months although each bee will emerge and complete its life-cycle within a matter of weeks.  The timing of the emergence of each species coincides with optimal temperatures.  For instance the Blue Mason Orchard Bee will be active in the cool of spring whereas leaf-cutters are active in the summer heat.  The time period that nests are constructed is helpful in identifying the resident.  Bee houses should be in place by mid-March.

Bee Identification

Palmer Penstemon w bumble bee cropPlace the house where it can be observed daily if possible.  Keep a journal on activities, description of the bees, materials that are carried to the nest and what material can be seen in the tunnel or used for the end seal.  Are there insects other than bees using the tunnels .  Watch for bees on your flowers and try to match them to ones at the nest.  What size, color and shape are they?  How would you describe their behavior?  Fast and darting? Hovering?  Slow and bumbling?  Do they have pollen balls on their hind legs or pollen on the underside of their abdomen?  What kind of flowers are they visiting?  Do you find them sleeping in the flowers?  Take close-up photographs. Click on the website links below to help identify your bees.

Note the difference between bees and yellowjackets and wasps.  Wasps and yellowjackets have narrow waists and are smooth and shiny whereas bees have at least some fur on their body.  Wasps are not attracted to nectar or pollen.  Many but not all bees have long stiff hairs on their hind legs where they carry pollen balls.  Click here for more information on identifying bees.

Locating Your Bee House

  • Female bees will  typically find your bee house easier if  they are attached to a large visible object such as a building or fence rather than hanging on a tree or post.
  • Make sure it does not swing  in the wind as this makes it more difficult for the female to find her nest and the motion may dislodge the larvae from its pollen food source.
  • Face the bee house preferably towards the east or southeast to help the bees warm up in the morning.  The bee house should be in shade in the afternoon to prevent brood cells from overheating,  as well as  shaded in winter to prevent early emergence.
  • The tunnels should be aligned horizontal or slightly facing downward to prevent water accumulating in the tunnel.
  • The house can be placed anywhere from 3 feet or higher.
  • If you have more than one house, place them around the yard to imitate natural nesting conditions and to reduce spread of parasites and disease between bee houses.

Maintenance for Your Bee House

  • Do not move the bee house while there is nesting activity as it may confuse the female bees causing them to abandon their nest.
  • In the winter, protect your bee house from bird predators by placing hardware cloth around it.  Make sure to remove the wire in spring so the emerging bees will not damage their delicate wings.  Or, store your bee houses in an unheated garage or outbuilding  that will stay at temperatures below 39 degrees.  Handle the bee houses carefully so as to not damage the brood cells.
  • After 3 or 4 years you may need to clean your bee house or replace it.  Several indicators will tell you that it is time for maintenance including no new nests that season, the sealed tunnels have not opened for over a year, or there is debris in the tunnel blocking it.
  • If the bee house needs cleaning but you suspect there are tunnels that contain live young, there is a way to let them emerge but not return to old nest.  Use a bucket with a tight fitting lid and painted black to eliminate all light inside.  A hole should be drilled in the bottom of the bucket.  In the spring, place your old bee house in the bucket and hang it near a new bee house.  The bee will emerge and, attracted by the light, will crawl through the hole and find the new house.
  • To clean the old bee house, re-drill the holes all the way through.  Then soak it in bleach and water (1:2) for 5 minutes and let thoroughly dry.

References

  • Bosch, Jordi, and W. Kemp.  2001.  How to Manage the Blue Orchard Bee As an Orchard Pollinator. Sustainable Agriculture Network, National Agricultural Library, Beltsville, MD. 88 pgs.
  • Cane, Jim and L. Kervin. 2009. Gardening for Native Bees in Utah and Beyond.  Utah State University Extension Service and Utah Plant Pest Diagnostic Laboratory, ENT-132-09.  Logan, Utah.  10 pgs.
  • Mader, Eric, M. Shepherd, M. Vaughan, S. H. Black and G. LeBuhn.  2011.  Attracting Native Pollinators, Protecting America’s Bees and Butterflies.  The Xerces Society Guide.  Storey Publishing, North Adams, Maine.  371 pgs.
  • Mader, Eric, M. Sheperd, M. Vaughan, and J. Guisse.  2009. Tunnel Nests for Native Bees, Nest Construction and Management.  Invertebrate Conservation Fact Sheet.  The Xerces Society for Invertebrate Conservation.  Portland, OR. 
  • Pollinator Workshop.  2010.  USDA Agricultural Research Service Bee Biology and Systematics Laboratory and Utah State Extension Service.  Logan, Utah.
  • Vaughan, Mace, S. Hoffman Black.  2007.  Enhancing Nest Sites for Native Bee Crop Pollinators.  USDA National Agroforestry Center, AF Note-34. 4pgs.

Websites of Interest