By Diane Wilson, Ecologist

Due to declines in the numbers of honey bees and wild pollinators, pollinator conservation has become a high priority in the United States, as well as other countries.  These declines have been caused by disease, pests, stress and habitat destruction.  There are 3 important requirements to consider for pollinator conservation: food, habitat, and safety.  Bees and other pollinators need food sources throughout their active season to insure good nutrition, which helps them to fend off disease and pests.  They also need habitat or areas where they can build nests and/​or lay eggs.  Finally pollinators need protection from disruptive or deadly landscaping and farming practices.  If you have all 3 of these areas covered, you will be well on your way to conserving, and even increasing, pollinator populations on your property.  Today, I will be focusing on habitat for pollinators. 

Natural or Semi-​​Natural Habitat

If you have natural habitat or wild areas on you property, you can simply set it aside for pollinators.  These should be left undisturbed if there are adequate floral and habitat resources available.  The majority of wild bee species are gound nesters, and a minority utilizes wood, stems or twigs to build their nests.  Bumble bees nest in cavities underground, under clumps of grass, or in holes inside trees or walls.  Butterflies need protected sites such as trees, shrubs, tall grass, or piles of leaves or sticks. 

An ideal area to set aside is wooded land, shrubland or grassland that has an abundance of nectar and pollen rich flowers as well as some open, bare or partially vegetated ground with well-​​drained soil.  If possible, leave old, dead trees and shrubs in place for wood nesting bees.  If you must cut down dead trees for safety reasons, leave some of the limbs lying on the ground.  If the area looks unkempt and slightly cluttered with natural debris, it’s probably the idea place.

Even if you don’t have natural habitat, there are numerous options that might be available to you.  Marginal farmland that is inadequate for crops is often perfect for pollinator habitat.  Other semi-​​natural, undisturbed sites include meadows, field edges, buffer areas, roadsides, hedgerows, drainage ditches, and out-​​of-​​play areas on golf courses.  Homeowners and commercial business owners can install a pollinator flower garden and add hand-​​made bee nesting sites or natural objects that pollinators can utilize for nesting and egg-​​laying.

Constructed Habitat and Artificial Bee Nests

If you don’t have natural or semi-​​natural areas for pollinator habitat, you can build your own.  Choose an area for the pollinator habitat that is away from places where people are active.  For a natural appearance, sow native bunch grasses and wildflowers together.  Bunch grasses provide better nesting sites for bumble bees.  For ground-​​nesting bees, keep some areas bare where the soil is well-​​draining, or create unvegetated or lightly vegetated berms or mounds of sandy or silty soil.  Poor soils are actually preferred over rich, fertile soils.  Sites for ground-​​nesting bees should be constructed in open, sunny locations.

For stem and twig nesting bees, you can make stem bundles, which are actually more like an apartment complex for bees.  These make great projects for children.  Like birdhouses, stem bundles are fun to make, and it’s exciting to see bees nesting in them.  Twigs of elderberry, sumac, raspberry, and blackberry are excellent for bees that chew out the centers of the stems to create their nests.  Bamboo stems, which are naturally hollow between nodes, can also be used for stem bundles.

To make a stem bundle, cut the twigs or bamboo into 8–12 inch long sections and tie them together with baling wire.  With bamboo, cut the pieces so that there is a node at one end and the other end is open.  The bundles should be about 3–5 inches wide so that you can still work with them by hand.  Creat a hook on the end of the wire to hang, or leave 2 long wires on the bundle so that you can twist them around posts, stakes, trees, fences or other sturdy objects in or near the pollinator habaitat.  The stems should be hung horizontal to the ground, and the bundles should be secured tightly so that they don’t move around by the wind.

For bees that nest in wood, you can simply drill holes in stumps, tree limbs, and blocks of untreated wood or lumber.  Use a variety of drill bit sizes, ranging from 1/​8 to 3/​8 inch.  For holes 1/​4 inch or less, drill the holes 3–5 inches deep.  For larger holes, drill 5–6 inches deep.  Set these wood objects in or very near the pollinator habitat. 

Maintenance

Once an area has been designated a pollinator habitat, then several maintenance practices should be followed.  Avoid disturbing the ground by digging, tilling, plowing or other means.  Never spray any insecticides in the area.  These will hurt or kill pollinators as well as the destructive insect pests they were meant to target.  Keep on top of weeds or unwanted vegetation by removing them periodically.  Finally, sit back and watch the pollinator activity for many years to come.

For more information, check out the Xerces Society for Invertebrate Conservation at www​.xerces​.org