ROSEVILLE, Calif. July 17, 2012— The Placer Mosquito and Vector Control District reports an increase in calls concerning yellowjacket wasps, especially in the western end of Placer County.

Summertime is when yellowjackets are expanding their nests, making them more active and visible.

Yellowjackets are often confused with paper wasps and mud daubers.  These insects may look alike and are all capable of stinging, but the differences in yellowjacket behavior make these wasps much more of a threat to the public. “Yellowjackets are highly aggressive and are capable of forming very large colonies with thousands of wasps,” explains Dr. Mary Sorensen, entomologist for the District.  The potential for human injury from yellowjackets is very high if the colony starts to swarm.  “Since yellowjackets can sting multiple times, even non-allergic people can have a serious reaction to the stings, and in rare cases, the sheer amount of foreign protein injected can cause kidney failure and even death,” she warns.  Paper wasps and mud daubers can be managed by the average resident, with the aid of a few items from the local hardware store.  Yellowjackets nests, on the other hand, need to be removed by trained professionals to minimize risk of injury for residents.

The public can implement the following measures to prevent yellowjacket problems:

  • When dining outdoors, cover food and beverages to discourage yellowjackets
  • Keep garbage cans closed with tight-fitting lids, rinse bottles and cans before placing in covered recycling bins

Residents are encouraged to contact the Placer Mosquito and Vector Control District for additional assistance in managing yellowjacket problems. For more information, contact the Placer Mosquito and Vector Control District at (888) 768-2343 or visit their website at