University of Maryland Extension

Yellowjackets

yellow jacket

Key Points

  • Yellowjackets are social wasps and their nests or colonies can contain thousands of workers by late summer/early fall.
  • Yellowjacket wasps cause the most stings of all bees and wasps. They are capable of inflicting multiple stings. Attacking yellowjackets release a pheromone (chemical) that calls other yellowjackets to defend the nest. 
  • Activity around a nest, particularly activity that causes vibration, such as from a lawnmower, weed trimmer, or hedge clipping, can cause angry yellowjackets to swarm from a ground nest and attack. 
  • Yellowjackets are considered beneficial insects because their food consists primarily of insects. But they do become aggressive, especially in late summer, and fall and are attracted to human food and drink. 

General Information

  • Adults are 3/8 to 5/8 of an inch long with a yellow and black striped abdomen.

  • There are several species of yellowjackets in Maryland. 
    • Common and eastern yellowjackets nest in the ground.
    • The German yellowjacket will nest in wall voids of buildings.
    • Aerial yellowjackets build paper nests on shrubs, bushes, houses, sheds, etc.

yellowjacket nest in ground
Entrance hole to a ground nest of yellowjackets. Sometimes the hole
is hidden.

Mohammed El Damir, Bugwood.org

yellowjacket aerial nest
Yellowjacket aerial nest
Jim Baker, North Carolina State University, Bugwood.org

  • Typically, yellowjackets are active into the late fall. A killing frost will kill the workers and males. In winter, nests can safely be removed. An inseminated queen leaves the nest and overwinters in a sheltered location. In early spring, she begins a new nest that enlarges over the season. 

Management

  • A nest located in a low-traffic area that won't be encountered by people or pets can be left alone. After a hard frost, the inhabitants of the nest will die.

  • Pest control operators have the ability to safely and effectively control a yellowjacket nest. Call a pest control company if you do not want to attempt to control the nest yourself, have an allergy or sensitivity to stings, or there is difficult access to the nest.  

  • Aerosol wasp and hornet sprays can be effective in controlling a nest. Some formulations can injure plants or damage painted surfaces so read and follow the label directions. Control should be done in the evening or in early morning so there is some natural light and when most of the yellowjackets are in the nest. Never shine a flashlight directly at the nest because yellowjackets will fly towards the light.

  • If the nest is in a wall void, behind siding, or underneath your home a professional pest control company should be consulted. Do not block a nest entrance hole in a wall of a building. Angry yellowjackets can chew through wallboard to escape. 

Rev. 2020

 

Maintained by the IET Department of the College of Agriculture and Natural Resources. © 2020. Web Accessibility

University programs, activities, and facilities are available to all without regard to race, color, sex, gender identity or expression, sexual orientation, marital status, age, national origin, political affiliation, physical or mental disability, religion, protected veteran status, genetic information, personal appearance, or any other legally protected class. If you need a reasonable accommodation to participate in any event or activity, please contact your local University of Maryland Extension Office.