Summer Fun Can Come With a Sting: Yellowjackets and Paper Wasps

Yellowjackets are already making the headlines this year, even though it’s early in the season. The San Francisco Chronicle and other NorCal newspapers reported a July 3 yellowjacket attack on more than 70 attendees of the Alameda County Fair. Apparently, the ground-dwelling yellowjackets were disturbed by a fireworks display in the fairgrounds arena. None of the victims, who ranged in age from a 6-month-old infant to a person over age 60, exhibited allergic reactions or required hospitalization, although some received multiple stings.

In the Seattle area, also over the July 4th weekend, at least five people were treated for anaphylactic shock from stings believed to be from yellowjackets in separate incidents, according to a Pierce County public health official.

A small paper in Northeastern Ohio recently published a follow-up story on a man who nearly died from stings last summer after he ran over a ground nest of yellowjackets with his lawn mower. He’s been receiving weekly doses of bee venom over the past year in attempt to build up his immunity, the Hudson Hub Times reports.

And last month in Atlanta, several police officers chasing a DUI suspect who had abandoned his vehicle following a high-speed car chase were stung and one seriously injured when they ran through a clump of kudzu, disrupting a swarm of yellowjackets.

YellowjacketThere are two types of “social wasps” in our Sacramento pest control region: yellowjackets and paper wasps. Of the two, yellowjackets are more aggressive and dangerous to humans. Yellowjackets will attack if their nest is threatened or, less frequently, if someone tries to swat them away from a food source. Paper wasps are less defensive, less apt to sting, and shy of humans unless their nest is located near a traffic-way such as a door or gate.

Both yellowjackets and paper wasps start building their nests in early spring, when a single queen emerges from winter hibernation as the weather warms. From spring to late summer, they forage primarily for protein, usually in the form of other insects, to feed their growing colonies. Later in the summer and early fall, the colony may have grown to as many as 15,000 individuals. Large amounts of sugar are needed to feed the queens and workers, and this is when they become more troublesome to humans. It’s not uncommon for swarms of yellowjackets or wasps to aggressively forage around trash cans, dumpsters or human picnics and barbeques, where they may crawl into soda cans and sting when the unsuspecting victim takes a drink.

The most common type of yellowjacket found in our Sacramento pest control area is the ground-nesting western yellowjacket, (Vespula pensylvanica), sometimes called the “meat bee.” Other types of yellowjackets common to Northern California include Vespula vulgaris, often found in dead trees in foothill or mountain terrain, and the German yellowjacket (V. germanica), which often nests in houses in urban areas. Most types of yellowjackets have distinctive black and yellow stripes on the abdomen and have a very short narrow “waist.” Paper wasps are larger, about an inch long, usually black or brown in color with red or yellow patches, and have a long slender “waist” and long legs.

Yellowjackets may build their nests in abandoned rodent burrows or even inside the walls of houses, where a hole in the wall may result from the insects’ work to expand the next space. The nest contains rows of cells and is enclosed in a paper envelope the insect manufactures from wood fiber and saliva. Other types of yellowjackets build hanging nests beneath eaves or tree branches. Paper wasp nests, usually built under eaves or branches, also contain rows of cells but are open, with no paper covering. A nest normally contains no more than 200 individuals.

Mud daubers, which may be mistaken for yellowjackets or paper wasps, build nests out of hardened mud. Mud daubers are usually not aggressive and rarely sting.

In most cases, a single yellowjacket or wasp sting does not cause serious injury. However, in some cases people have allergic reactions that can be life-threatening—even when previous stings caused no reaction. The risk of a severe reaction increases with multiple stings.

Initial symptoms of a sting usually will be pain, redness and swelling. In more severe cases, the victim may have hives, nausea, vomiting, abdominal cramps or headache. Symptoms of severe allergic reaction typically occur within 30 minutes and may include shock, dizziness, unconsciousness, difficulty breathing, and swelling of the throat. Anyone exhibiting this type of allergic reaction must receive immediate emergency medical attention—call 911.

Unlike honeybees, whose barbed stingers are usually left in the victim’s skin, yellowjackets and wasps can sting repeatedly. The best thing to do if you are attacked is to leave the area.

Here are some tips to avoid stings, courtesy of University of California Statewide Integrated Pest Management System:

  • Avoid areas where a yellowjacket or wasp nest is visible. If you do go into an area with bee or wasp activity, wear long pants and a long-sleeved shirt. A mosquito/gnat veil can be used to protect your head.
  • Avoid wearing perfume, cologne, or scented soaps in areas where there is bee and/or wasp activity.
  • Wear shoes when walking through vegetation, especially clover or other blooming plants.
  • Avoid brightly colored clothing.
  • If a bee or wasp lands on your arm, try to remain calm until the insect leaves, or brush it away gently and slowly with a piece of paper.
  • Insect repellent applied to your skin or clothing will not protect you from stinging insects.

For more information about yellowjackets, wasps and other stinging insects, feel free to call our experienced Sacramento pest control professionals at 916-457-7605.

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