Did you know there are tens of thousands of known species of wasps worldwide? While we’re most familiar with the social wasps living cooperatively in large nests, like yellowjackets and hornets, the majority of wasp species are solitary, working alone or sometimes in small communal nests where they focus only on their own offspring.
In spring, a fertilized social wasp queen (storing sperm in her body) emerges from hibernation and starts a colony by laying female worker wasps. The workers continue to increase the size of the nest as the queen lays more eggs, culminating in laying male and queen eggs late in summer. By autumn, all the wasps (thousands per colony) die off, leaving only the inseminated new queens in sheltered hibernation to start the cycle again the following spring.
For solitary wasps, the life cycle is based on laying eggs and providing food to the emerging larvae. Sometimes the eggs are laid on a host or enclosed with paralyzed prey in varying ways, with the goal for the larvae to consume the host or prey on their emergence. Larvae can overwinter to emerge in spring.
It takes a while for a wasp colony to reach a significant size, so you probably won’t notice them until later in the summer. Last summer saw a notable increase in wasps and yellowjackets due to warmer temperatures and drought conditions as they sought new food and water sources.
If nests are in out-of-the-way spots, you can ignore them as they will die in autumn. If they are in areas you use regularly, you can take precautions to discourage them. Before you call a professional for removal, cover garbage cans tightly, pick fallen fruit and take care with water sources to minimize opportunities to be stung. Cover pet food bowls.
Acidic bee venom is very different than alkaline wasp venom, so people will react differently to their stings; people can be allergic to one and not to the other. While a bee will die in the act of stinging, because the stinger remains in the skin and damages the bee’s abdomen, wasps can sting over and over. Even worse, many of the social wasps (and honey bees) may also exude an attack pheromone that will incite others to attack skin or material with the pheromone on it, so a single sting can turn into many.
Solitary wasps typically sting only when mishandled or trapped in clothing. Solitary wasp venom is not as dangerous as social wasp venom and typically causes only brief pain.
When we worry about wasp stings, we’re really worried about the social wasps, which aggressively sting to protect the nest. Their venom can cause anaphylactic reactions in allergic individuals which can range from swelling and rashes to respiratory distress and even death. If you are allergic or have a heart condition, don’t take a chance with nest removal.
Before you go on the attack to eliminate wasps, be sure they are really a problem for you. Wasps have an important role in eliminating insects that cause far worse damage to plant life. The insecticides you use on wasps can also cause problems for beneficial insects we want to encourage, like pollinators.
Try trapping before using insecticides. The Northwest Center for Alternatives to Pesticides (pesticide.org) has ideas for creating and baiting traps and killing the trapped wasps.
Hornets will generally nest high enough to not be a problem, but yellowjackets will choose a variety of sheltered locations, to include underground burrows abandoned by other animals.
If you must remove a yellowjacket nest yourself, take careful precautions. Use protective clothing around the nest when treating and when examining to determine where the nest entrance is (the entrance is the focal area for treatment). On a cool night, when the yellowjackets will be inside and calm, follow all the label directions to treat the nest with the least toxic option available (the label will say “caution” rather than “danger” or “warning”). Don’t use a flashlight or other light as it will attract the yellowjackets.
If you’d like to know more about the differences between wasps that might sting and those that are unable or unlikely to sting, or you’d like to learn about do-it-yourself wasp management options that help you reduce the risk of being stung while also minimizing impact on the environment, please attend the workshop “Common Stinging Wasps Around the Home: Management Options.”
This workshop will teach you about what you can do before you call a pest management professional or apply a pesticide. It covers the physical appearance and biological differences between common wasps around the home and yard, and effective methods for homeowners to reduce encounters with stinging wasps.
Emphasis will be on integrated pest management for homeowners: non-chemical options to prevent and suppress common stinging wasps, and the judicious use of least-toxic chemical options as a last resort. Following the interactive talk, the instructor will lead participants in a walk around the property to identify and discuss wasp habitat in the built environment.
Susan Cox is a Master Gardener volunteer for the WSU Clark County Extension.