A reader asked us if we knew how to deal with some pesky ground-nesting bees that have made their home in potted plants in her nursery. She’s concerned that they might bother her customers, so we did some research and found out lots of interesting things.
Ground-nesting bees are part of a large group of natives called solitary bees who are not usually aggressive and rarely sting. They live and reproduce in tunnels that they dig into the ground (or in potted plants). They seem to like to nest near each other and their spring nesting activities, which last four to six weeks, may make them more noticeable.
We humans seemed to have found a way to make life difficult for our native bees, especially in urban settings (by definition this is anything that isn’t rural). In California between 60 – 70% of native bees live in underground tunnels (Urban Bee Gardens) and they need access to bare soil in order to build their nests. But we gardeners love to mulch and when we do we’re covering large areas of potential nesting sites.
If you do need to do something about ground-nesting bees in your yard, the University of Michigan Integrated Pest Management site says it’s best to deal with the bees by using cultural controls. Ground-nesting bees prefer well-drained soil containing little organic matter. Covering the affected area with mulch or ground cover and watering it regularly will discourage them.
Keep in mind though that these native bees have a very important role in pollination. Their place in the ecological system is especially vital because they are not subject to the human-caused health problems that plague honeybees and if honeybee populations continue to decline, solitary bees will become ever more important in pollinating wild plants, crops, and landscape plants. So discourage them where you must, but consider dedicating an out of the way area of your garden to the bees by keeping it dry and free of mulch, especially in urban areas where they need all the help they can get.