Q: I’m starting to notice bees and wasps in my garden. What can I do to get rid of them?
A: Bees, some of the most beneficial pollinators in our landscapes, have the misfortune of looking similar to much more troublesome and aggressive insects, yellowjackets. In fact, at least 90% of reported “bee stings” are actually yellowjacket stings. How to tell the difference? First of all, honey bees and bumblebees are hairy, almost furry, and this hair is not difficult to see. Yellowjackets and other paper wasps are smooth. Secondly, bees are generally focused on gathering pollen and nectar from flowers. They are especially attracted to blue and purplish-blue flowers. When you see a vibrating catmint flower (and blue mist spiraea in the fall), that movement is caused by bees moving from flower to flower (this is a good opportunity to get a close look at them to see their “fur”). Yellowjackets, which eat dead insects, garbage, and other meat-based foods, are more likely to be flying around your food or drink, hovering around a trash can, or harassing you while you are trying to relax outside.
Controlling bees is not usually needed and is indeed not recommended unless they have established a colony in a building’s wall cavity – a rare occurrence. They are not aggressive and will only sting if accidentally stepped on (with a bare foot) or trapped in clothing, or if their nest is threatened.
Controlling yellowjackets can be difficult, but this is the time of year when you can have the most effect. First, eliminate any food or water source that is near where people will be spending time outside. This includes sealing up and moving garbage cans and not leaving pet food outside. Early in the season (May and June, so NOW), traps sold for yellowjackets are useful because queens and scouts can be trapped before they establish colonies and nests. So at this time of year, you won’t get as
many yellowjackets in your traps as later, but the ones you catch are important and will reduce those later numbers. Another step to take early in the season is to seal or cover any openings and cavities around your house (like vent openings for dryers, for example) or in playground equipment that might be tempting nest sites. Later in the season, treating and eliminating established nests is more effective. Since yellowjackets usually nest in the ground, and they travel up to 1000 ft away from their nests, finding the nests can be difficult. (But if you get near one, they’ll let you know!) However, they will sometimes nest in wall cavities, getting in through cracks or cold air returns. Many insecticides are sold for eliminating wasp nests – multiple applications are usually needed for ground-nesting yellowjackets.
Often people think that yellowjackets or bees are nesting in those big gray papery nests that hang from tree branches, eaves, etc. Those nests house other much less aggressive paper wasps. If the nest is actively causing a problem, it can be treated with the same insecticides mentioned previously. Otherwise, wait until it is abandoned in the fall. It will not be used again and can either be removed or left to break apart on its own.
For more information on and pictures of bees and wasps, see the Colorado State University Cooperative Extension Fact Sheet, “Nuisance Wasps and Bees” at www.ext.colostate.edu/PUBS/INSECT/05525.html
Contributed by Carey Harrington, Colorado Master Gardener. Honey bee and yellowjacket photos from fact sheet 5.525. Bumblebee photo courtesy of Tom Harrington. For answers to your horticultural questions, contact the Master Gardener Help Desk at 636.8921 or CSUmg2@elpasoco.com. Access fact sheets and seasonal information on the El Paso County Horticulture website http://elpasoco.colostate.edu/horticulture/.