Wasps, Yellowjackets, and Hornets

 

 

There are several groups of insects that commonly get lumped together as "wasps" including hornets, yellowjackets, paper wasps, and mud daubers.  Although all wasps will defend their nests, yellowjackets and hornets are the most aggressive and are the ones that cause the most problems.  They can be distinguished from bees by their thin "waists" (bees are thick-waisted).  The wasps that seem persistent at picnics and outdoor meals are yellowjackets, looking for meat, proteins, or sugary foods or drinks.  Yellowjackets become more aggressive and likely to sting in late summer and early fall, when the colony is declining.

 

When considering control of wasps, bear in mind that they are also beneficial, killing many pest insects to feed to their young.  If the nest is situated in a location that is not likely to be bumped or disturbed, you might consider letting the wasps remain in the area to serve as beneficials.  The colony will remain active for only one summer, after which the queens will fly away to start colonies of their own.  The ones that remain behind die at the end of summer, and the nest is not used again.

 

If removal is necessary, the best option is to get professional help from a pest control company or a bee keeper, because any disturbance around a nest can trigger a mass attack.  If you choose to do it yourself, complete body coverage and protection is essential, because yellowjackets can find even small openings in clothing.

 

Treat nests in early morning or in evening when wasps are less active, using a commercial wasp and hornet insecticide that can be applied from a distance.  Foggers containing pyrethrins or resmethrin can also be used.  Pressurized sprays containing diazinon or resmethrin can be applied as aerosols.  Sometimes these will only act as a repellant, driving the yellowjackets into the nest long enough to tear the nest down, place it inside a heavy plastic bag and apply lethal doses of the insecticide into the sealed bag. 

 

Poison baits containing diazinon can also be used effectively if worker wasps carry enough of the bait back to the colony to kill the queen and the immature wasps inside the nest.  This type of bait is available from pesticide distributors.  When using any pesticide, whether it is natural or synthetic, be sure to read and follow label instructions and precautions.  Wear protective clothing, including rubber gloves and boots to protect yourself from the insecticide.

 

Gasoline is not a good control option because of the fire hazard, the angry swarms of wasps, and contamination of soil and possibly groundwater.  Again, you may want to consider leaving the nest be, if possible, and allowing the wasps to function as beneficial insects.

 

To manage wasps at picnics and around food concessions, hang a piece of meat or fish over a gallon container of soapy water.  When these insects leave the hanging bait, they often drop down a short distance before beginning to fly, dropping into the water.  Braunswagger sausage is said to work well.

 

References:

Cranshaw, W., M. Brewer, S. Armbrust, and S. Lajeunesse.  1994.  Household Insects of the

Rocky Mountain Region.  Extension Publication 557A, Montana State University, Bozeman, Montana.  90 pp.   

Guide to Structural Pests.  National Pest Control Association, Dunn Loring, Virginia.  

Olkowski, W., S. Daar, and H. Olkowski.  1991.  Common-Sense Pest Control; Least-toxic Solutions for Your Home, Garden, Pets and Community.  Taunton Press, Newtown, Connecticut.  715 pp. 

Urban Integrated Pest Management- A Guide for Commercial Applicators.  1992.  Environmental Protection Agency.  EPA Manual 734-B-92-001.  Washington, D.C.

Written by Sherry Lajeunesse, Extension Urban Pest Management Specialist.  Sept., 1997

Categories: Wasps, Yellowjackets, Hornets, Bait

Date: 1/17/2002