Last week while we were nearing petal fall in the Champlain Valley, a grower and I were discussing when he ought to take his honey bees out of the orchard, which led us to discussing the role wild bees are playing in his orchard. These wild bees help pollinate our crop every year, so I think it is worth reviewing some of the different kinds of bees we can expect to see at bloom, and what we can do to encourage their visits.

Over 100 wild bee species visit orchards in the Northeast.  Many of these bees are native, and can be very good at pollinating fruit trees when their populations are in sufficient numbers close to the orchard. 

Unlike honey bees, many wild bee species are solitary, living in their own nests. Some of these bees build nests underground, and are therefore referred to as ground nesting bees. Bees in this group include cellophane bees, mining bees, and sweat bees.  These bees prefer to build their nests where the ground is bare and the soils are well-drained, so a relatively simple way to increase these pollinator populations near your orchard is to leave some areas of ground free of vegetation.

Tunneling bees are another common group of wild pollinators. This group tunnels into dead trees and wooden structures, or takes up residence in other open cavities. This group includes mason bees and carpenter bees.  To increase your farm's tunneling bee populations, consider maintaining a woodpile on your property that the bees can use a nesting site. Having hedgerows and wooded areas around your orchard blocks will also provide good nesting areas. If you would like to take an even more hands-on approach, you might consider building nesting boxes to place on the edge of your orchard.

A third common group of pollinators includes honey bees and bumble bees. These bees are social, living together in groups, and build their nests into preexisting cavities. Similar to what you might do to increase populations of tunneling bees, having wooded areas near your orchard blocks will help bring more cavity nesting bees into the orchard at bloom, as will having a woodpile nearby. 

In addition to providing areas in your orchards for nesting sites, wild bees need to have enough flowering plants throughout the growing season to forage while the fruit trees are not in bloom. Some bees, like bumble bees, are active throughout the entire growing season, while our apples might only be in bloom for a week. Since many orchards in Eastern NY are located near wooded areas, there are many wild plants in bloom around the orchard throughout the growing season already. You and your neighbors probably have many other flowering plants on your property, and weeds along the roadside also provide a food source for the wild bees. To hedge your bets further, you may consider planting a few strips of flowering plants near your orchard blocks. Just be sure to choose plants that do not bloom at the same time as your fruit trees.

Distance can be an important factor in how well wild bees may help pollinate your blocks.  Some bees, like honey bees and bumble bees, can fly over a mile from their nests, while others may fly less than 500 yards from their nesting site.  This may limit wild bee pollination in blocks where a large portion of the trees is over 500 yards from the periphery of the orchard, where nesting sites and other food sources are available. 

So, while honey bees will continue to be our go-to pollinators, you might consider some of the small steps you can take to make your site even more attractive to our wild pollinators. 

For more detailed information, including color photos of the bees mentioned here, please see the publication Wild Pollinators of Eastern Apple Orchards and How to Conserve Them by Mia Park et al., 2012.

Citations:

Park, M., et al. 2012. Wild Pollinators of Eastern Apple Orchards and How to Conserve Them. Cornell University, Penn State University, and The Xerces Society. URL: http://www.northeastipm.org/pa...