Vespid wasps (Vespidae) are the family of social and colonizing wasps that are very aggressive and give all wasps and bees a bad name. Vespid wasps include paper wasps, yellow jackets, and hornets. These flying insects have no body hair and thinner, elongated bodies.
Most wasps are beneficial pollinators of plants and predators of other insects, but when vespid wasps build close to our homes, barns, and recreational areas, people and animals are endangered. In defending their nests, they can sting multiple times, causing intense pain and sometimes, severe allergic reactions and even death.
Most stings occur near the wasps’ nests. They rarely sting away from the nest unless they are trapped or pressed against the skin. During outdoor summer activities, be careful where you walk and sit, always notice the environment around you. All these wasps can call other colony members using alarm pheromones. These chemical messages are like an airborne email blast that will bring on the wasp cavalry so you will want to get out of the area in a hurry.
Paper wasps are reddish-brown in color and less than one inch long. They build their open, umbrella-shaped paper nests from chewed wood fibers that are constructed new each spring. A queen wasp lays a single egg into each of the hexagonal-shaped cell of the comb. The eggs hatch into larvae, which eventually become pupae, and then mature into adult worker wasps. Protein is needed to feed these babies, and worker wasps bring dead or paralyzed bugs to the nest. At the height of the summer, a nest will house less than a hundred wasps. In late summer and fall, males and queens are produced. When mature, they fly away from the nest and mate. The male wasps soon die, and the fertilized queens find a sheltered spot to hibernate through the winter. In the spring, the cycle begins again.
Yellowjackets are ground nesters and the most aggressive of the bunch of vespid wasps. They have bright yellow and black bodies with a well-defined waist and thin legs. They also help keep the bug population in check by feeding captured insects to their young. As the summer season wanes, they scavenge further distances for more food sources and have an increased need for sugar and carbohydrates. This brings them to your picnic or garbage cans.
Yellowjackets will build their nests in old rodent holes or cracks in stone walls or crevices of rotting stumps. At peak season as many as 20,000 yellowjackets will inhabit a single nest. Because they live in the ground, they are sensitive to vibrations such as lawn mowers or other powered gardening tools and will aggressively defend their nests. Always inspect your lawn before mowing. Watch for insects coming in and out of the ground. Once disturbed, hundreds of yellowjackets will pour out of the nest and aim for the head of any animal or human in the vicinity. Their ability to inflict multiple stings can cause tremendous pain and sometimes death.
Hornets construct a round or pear-shaped paper nest that can be up to three feet long. Inside it has two to four horizontal combs with a single entrance at the bottom. These hanging nests may be attached to trees or high in the eaves of buildings. A mature colony will contain several hundred insects. Hornets are less likely to attack than paper wasps and yellowjackets, but if provoked, their attacks can be dangerous and painful. Different species of hornets have different levels of venom; some are among the most venomous of known insects.
All the vespid wasps play an important role in the insect ecosystem. If their nests and activity are not near humans or animals, you are encouraged to leave them alone. The colony will die out in the winter, and the new queen rarely returns to the old nest. If danger of stings is a possibility, you are encouraged to call a professional to eliminate the nest. If you choose to destroy the nest yourself, plan your attack at dusk when all the wasps have returned to the nest. Wear protective clothing, completely covering all of your body from head to toe. If using chemical sprays, carefully follow the instructions on the label. Remember: The Label is the Law. Spray the nest, then leave the area immediately. Return the next day to evaluate your success. It may take up to two days for all the wasps to die off, and then you can destroy the nest. Do not use gasoline or other toxic materials on the nest that would pollute the environment.
Robin Volker is an OSU Extension Master Gardener Volunteer.