By Gerry Hernandez, UC Master Gardener
Yellowjacket wasps prey on other insects and scavenge on human food and garbage. Yellowjackets defend their nests, as do other social wasps and bees, but are more likely to sting if disturbed while foraging.
First, do you have yellowjackets? They are ½ to 1-inch-long with jagged bright yellow and dark black stripes. Their narrow waist is barely visible. Unlike other common wasps, yellowjackets scavenge on food. They nest in holes in the ground, inside wall cavities or in hanging nests enclosed in gray paper.
Paper wasps have long slender waists, build open paper nests under eaves and are rarely aggressive.
Mud daubers are dark-colored and thread-waisted, they build small, hard mud nests.
How do you control yellowjackets? Keep food including pet food covered or indoors. Cover soda cans so wasps don’t crawl in. Keep garbage in sealed cans and empty regularly. Pick up and dispose of ripe fruit.
Yellow lure traps hung along the perimeter of a property can reduce foraging of some species around patios or picnic areas. Place traps away from areas such as picnic tables where people congregate.
If you choose to treat nests, wear protective clothing on your body, hands and head. Use an insecticide that shoots a long stream into the nest entrance. To protect yourself and your family, consider calling a professional if you find nests.
If a wasp lands on you, don’t swat it or run. Wait for it to leave, or gently brush it away. Do not disturb nests. Wasps flying from a hole in the ground, or a building indicate a probable nest.
Source: University of California Agriculture and Natural Resources. Visit ipm.ucanr.edu or cecolusa.ucanr.edu.