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Bug of the Week is written by "The Bug Guy," Michael J. Raupp, Professor of Entomology at the University of Maryland.

Be careful around yellow jackets: Eastern yellowjackets, Vespula maculifrons

 

Yellowjackets often stop by picnics to share snacks like applesauce.

 

Last week while attending a workshop, I was asked by a friend about a rash of nasty encounters with stinging insects, wicked bands of furious yellowjackets and bald-faced hornets that assaulted workers as they trimmed vegetation. Yellowjackets are among the most aggressive of stinging insects found in Maryland. Unlike the European hornets we visited in a previous episode, these gals seem to seek vengeance with little provocation.

Several species of yellowjackets are found in the mid-Atlantic region. Ones often nesting in my backyard are natives, the Eastern yellowjacket, Vespula maculifrons, but the non-native German yellowjacket, V. germanica is also found in our area.  In our area, the femme fatales of these species spend the winter in protected locations outdoors and initiate new colonies in spring. Some yellowjackets nest in the ground and others build papery nests in shrubbery. The colonies can be completely underground, within wall voids or man-made structures such as sheds or old cars, or in dense shrubs or vegetation. Nests are made of papery chambers that serve as incubators for the developing brood of larvae. Brood combs are enclosed in an outer shell of paper.

At the nest in my back yard, some workers remove balls of soil to enlarge the colony, one snips the root of a plant near the entrance, and others return with food for the young.

Unlike the nests of bees, the nests of yellowjackets contain no honey or pollen. Yellowjacket larvae eat meat and carbohydrate rich foods gathered by the workers. In this regard, yellowjackets are beneficial because they kill many caterpillars and beetles that are pests in our gardens. By late summer and early autumn, colonies may contain thousands of workers and are often about the size of a football. Under extraordinary circumstances, some nests may persist for more than one year and reach gigantic proportions. There are reports of monster yellowjacket nests in southern states reaching the size of a “Volkswagen Beetle”. Yikes! I sure wouldn’t want to bump into one of those with the lawn mower.

In late summer and autumn, new queens are produced in the colony and workers become manic in their attempts to gather enough food for the developing royals. Feisty workers are common around trashcans, fruit trees, and outdoor eateries where they gather protein from sandwiches and sweets from fruit or open cans of soft drinks. Be careful when you picnic. Look at a potential picnic spot and select a table or patch of lawn removed from trashcans that may be buzzing with hungry bees and wasps.

Natural sources of carbohydrates include honeydew from scale insects.

Yellowjackets often enter drink cans in search of sweets. These unseen guests can really liven up a soft drink, but swallowing one is dangerous. Instead of drinking from cans that may contain yellowjackets, use cups or clear bottles that allow you to see what is in your drink. Drink boxes with straws are a good choice for children to reduce their risk of imbibing a yellowjacket or bee. If you encounter stinging insects at your picnic table, gently brush them away from your food rather than swatting them or flailing your arms. Quick aggressive movements on your part may be rewarded with the same by a yellowjacket.

Levels of yellowjacket aggression seem to increase during late summer and autumn, when nests have legions of maniacal workers willing to die to defend the colony. If you blunder upon a nest in the lawn or in a bush, walk away as quickly as possible with a minimum of swatting and arm waving. Walking through a bush (no, not one with the nest) may help throw the pursuing workers off your trail and help you escape without stings. When attacking, yellowjackets release a chemical signal called an alarm pheromone into the air. Like a charge call from a bugle, it incites other yellowjackets to enter the fray with deadly intent.

The venom of yellowjackets and their kin has evolved to bring maximum pain to vertebrates like skunks that pillage their nests. Encounters with these fierce ladies confirm that their venom brings agony to humans as well. Yellowjackets are capable of multiple stings, but only to a limited extent. Contrary to common belief, they have barbs on their stingers and many lose their stingers and internal organs during a fatal attack. If you are stung, apply ice to the site of the sting to reduce some of the damage and pain. Sting relieving ointments and creams are available in pharmacies and sporting goods stores and may help reduce the pain and itching. If you know that you are allergic and are stung, seek medical attention immediately. If you are stung and experience symptoms such as shortness of breath, difficulty breathing or swallowing, hives on your body, disorientation, lightheadedness or other unusual symptoms, call 9-1-1 and seek medical attention immediately. Desensitization therapy has proven very helpful to many people with allergies to stings of bees and wasps.

Lil’ Rover demonstrates what happens when you sit on a nest of yellowjackets, but don’t worry! Lil’Rrover has thick fur and was not harmed in the making of this video.

If you know of a yellowjacket nest and the nest is unlikely to be encountered by humans or pets, you may simply leave it alone. If the nest is in a place that threatens you, children, or pets, you may consider eliminating it. Commercial pest control operators can assist you in this. I have purchased aerosol sprays, applied them according to the instructions on the label, usually at night or in the evening, and had excellent success. Please be careful around these fierce ladies or you might feel the wrath of stung.

References

Bug of the Week thanks Dr. Nancy Breisch for sharing her expertise and knowledge about stinging insects. Peter Becker provided the inspiration for this episode.

For more information on yellowjackets and their stings, please visit the following web sites:

http://ento.psu.edu/extension/factsheets/eastern-yellowjacket

http://www.webmd.com/skin-problems-and-treatments/insect-stings