Hundreds of digger bee nests, the light tan colored spots, in Setauket property. Photo by Rachel Shapiro
March 20, 2012 | 12:44 PMOne of the frustrating parts of gardening is dealing with garden pests. Those of you who have read my column for any length of time know that my philosophy, for the most part, is live and let live, unless the situation creates a major problem. Recently, I was told about an unusual local situation, potentially a major problem.
Todd Freund of Setauket noted hundreds of small mounds, about two or three inches tall, in the ground near his property. Hundreds of bees were flying in and out of the mounds.
Cornell Cooperative Extension of Suffolk identified them as digger bees (also called ground bees or burrowing bees). When Freund called the police, concerned about a potential danger to local children, they suggested he contact an exterminator. But since the bees are not on his property, that's not really an option.
"In my 78 years living on Long Island, I've never seen it," Freund noted. There are, he added, perhaps a thousand of these mounds along five or six pieces of property.
I've never seen such an infestation either, but some research I've done suggests that approximately 60 percent of all bees in New York State are digger bees.
Why Freund has never seen digger bees before makes sense when you understand the habitat they prefer: dry, sandy soil with few plants. Most people who live on Long Island have well-watered lawns, growing in soil to which compost has been added. While some people consider digger bees as "lawn killers," in all probability, it's the other way around. The ground was dry, sandy and with a sparse lawn and therefore attractive to the bees.
Digger bees are solitary, in that they don't build a hive. Each female builds a nest in the ground. Only the females, who stay primarily in their nests, can sting. For the most part, unless threatened they are very docile. The males, although more aggressive, can't sting. When you see many digger bee nests it's not because they are a colony, but because it's an ideal area for them to nest.
Digger bee nesting in property in Setauket. “It’s an infestation like I’ve never seen before,” noted Palifka. Photo by Alicia Palifka
Now, what does the gardener do about digger bees?
The answer has several parts.
• The immediate solution is to give the area where the digger bees are nesting a wide berth. Do not mow that part of the lawn. They are not typically aggressive, so if you don't bother them they probably won't bother you. Bees provide a valuable service in nature, namely pollinating plants. So, eliminating them totally from the landscape would be counterproductive.
However, and this is a big however, if you or a family member is highly allergic to bee stings, you may want to call in a professional to deal with them.
• The short-term solution is to let nature take its course. Adult digger bees are only seen in April and May (yes, I know it's still March, but it's been a very mild winter so everything seems to be ahead of itself). They typically live for four weeks during which time they mate, construct a single celled nest, lay eggs in it and then die off. For approximately 11 months out of the year, there are no adult digger bees around. The eggs hatch underground and digger bees overwinter as larvae and emerge as adults come next spring. So, wait for a few more weeks and they'll be gone.
• The long-term solution is to eliminate the conditions that attracted the pests in the first place. People who have lots of moss and want grass, for example, need to change the soil pH to alkaline and get more sun into the area so that grass can take hold instead of moss.
Well, since digger bees like dry, soft, sandy soil, with little or no vegetation, the long-term solution — after all the adult bees have died off — is to make sure that the area is well watered, add compost and plant shade-tolerant grass. Shade tolerant grass is suggested since many areas where grass doesn't grow well are shady. Make sure to fertilize the grass so that it will grow in nice and thick.
The University of Georgia College of Agricultural and Environmental Sciences suggests that if grass doesn't grow, then mulch the area well. They also note that since the bees are generally not harmful and pesticides are toxic, it's best to put up with the bees for the short term.
Ellen Barcel is a freelance writer and master gardener. To reach Cornell Cooperative Extension and its Master Gardener Program, call 727-7850.