We have had more phone calls than normal this fall about yellowjacket wasps. Many callers are concerned that they have "bees" and want to know how to save the pollinators. Deciding the desired course of action in this situation requires we take a step back (literally and figuratively) and make a confirmed diagnosis.
Diagnosis starts with a simple question: What color are the “bees" followed by, Are the "bees" coming from a hole in the ground.
Recent experience suggests that approximately 90% of the inquiries we receive about “bees” in the ground or in a house wall are not bees, but rather are yellowjacket wasps.
The difference between honey bees and yellowjackets is easiest to determine by color (they are the same size and shape and behave similarly). Yellowjackets are bright yellow with black markings and shiny. Honey bees are golden brown and fuzzy. Honey bees never nest in the ground. See photo below.
Yellowjacket wasp colonies are annual – they start from scratch every spring and do NOT reuse an old nest. The new females produced in the fall of the year are able to hibernate after mating. All other members of the original nest – the old queen, the workers and the males -- will die when it freezes.
Yellowjackets are not effective pollinators but they are beneficial. Yellowjackets feed on other insects during the summer and are a beneficial predator. This benefit diminishes by late summer as the queen stops laying eggs and the colony stops collecting insects to feed to her larvae. Wasps can be controlled in late summer with little effect on the ecosystem (unlike honey bees which have perpetual colonies that persist from year to year in the same location).
There are two options for yellowjacket control: One is to do nothing and wait for the colony to die in early winter. Cheap and easy, but the down-side is you have to put up with the risk of being stung until the weather gets colder.
The second option is to puff insecticide dust or powder into the nest opening at night. There is very little chance of being stung at night or when they are not active. Insecticide dust will be more effective than a spray that will mostly soak into the ground or concrete. Dusts are harder to apply, especially for nests not located at ground level. Garden insecticide dust such as Sevin or household insecticides such as boric acid powder work well for this.
See the Yellowjacket Page on the Plant & Insect Diagnostic Clinic website for more details.