Thursday, May 21, 2009

Turf and Landscape - Ground Nesting Bees

The following is a good article on ground nesting bees, a common issue you may find in turf and landscapes. These are often benefical pollinators and should not be controlled unless absolutely necessary.

Several bee species nest in the ground; they can be seen entering and leaving pencil- diameter holes in sunny areas of sandy or well-drained soils covered with a sparse grass stand. These entrances are often surrounded by small mounds of fine soil particles. Many of these bees live in individual tunnels where they raise their young but over time, sizeable communities can develop where conditions are favorable and nearby flowers are abundant. They can sting if handled or stepped on but do not aggressively defend their nests.

Control may be warranted on children's play areas or if excessive tunneling is creating bare spots. However, ground bees select and thrive in areas that meet their requirements. While insecticide applications may have some temporary effect, the factors that make the sites attractive remain unchanged.

Carbaryl or Sevin, applied to burrowed areas according to label directions for turf pests, can reduce ground bee activity. However, this approach is a temporary solution. The bees are nesting there because the site is attractive - well-drained or sandy soil with relatively a sparse grass stand. Site alteration is needed to provide a long-term solution. Over-seeding bare areas, adequate fertilization, and watering should improve turf stand make areas less attractive to these bees. Raising the mowing height may help, also.

Most ground bees are 3/8 to ½" long and vary in color from solid black to brightly metallic and have "hairy bodies". These "wild" bees are important pollinators and should be left alone if they are not causing a problem.

There are many important pollinating bees in addition to the familiar honey bee. These small, hairy bees tunnel into well-drained soils where grass cover is thin. Females may share entrances but dig separate tunnels with side branches for brood rearing. These bees collect pollen and nectar and bring them back to the nest to feed their larvae. They do not harm the turf. Ground bees can sting but generally are not aggressive and do not defend their nest area like honey bees. However, they pose a potential problem in children's play areas. In these cases, Sevin dust or other insecticides labeled for turf can be used to treat the entrances.

Reprinted from "Ground-Nesting Bees" By Lee Townsend in the current edition of the Kentucky Pest News

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