Technical Papers

NJ Homeowner's Guide to Yellow Jackets

Wednesday, August 12th, 2015 by Bill Cowley

Yellow Jacket

Yellow jackets are aggressive, territorial wasps, with distinctive yellow-and-black coloration, that are known for their propensity to sting anyone and anything that they perceive as a threat, such as those who venture too close to their nests or their food.

Physical Characteristics:

Yellow jacket workers range from 3/8 to 5/8 of an inch while queens are slightly larger at approximately ¾ of an inch. Like other wasps, yellow jackets have six legs and antennae. Most species of yellow jackets have black abdomens with a yellow pattern that looks like bands around the insect. Bumble bees have a similar color pattern. However, bees and wasps can be distinguished by their shape and body texture. Bees are more full-bodied than wasps and have hairy bodies. Wasps are slender with a narrow waist connecting their thorax (mid-section) and abdomen (rear section). Wasps also appear smoother and shinier, and have slender legs shaped like cylinders.

Reproduction:

Yellow jackets are social wasps that live in colonies. In the Mid-Atlantic states, a yellow jacket colony begins in spring after the queen emerges from her overwintering site, often in a rotting log or under a tree’s bark. When the queen first emerges, she feeds on nectar and eats prey, usually other insect). When sufficiently nourished, her ovaries enlarge and she will begin searching for a nest site. The queen commonly finds a nesting site underground, however, occasionally above-ground nesting locations like trees, attics, or soffits are used. Yellow jacket nests are made of a paper that the queen creates from wood or other plant material. Initially, the nest contains less than fifty cells for the queen to lay her eggs. When this first batch of workers emerge, they take over foraging and nest-building, allowing the queen to focus on what she alone can do, laying eggs.

The colony will grow throughout the summer. Depending on the availability of food, the number of predators near the nest, and the weather, the nest can grow rather large, potentially exceeding 4,000 workers. Most colonies reach their peak by August. At this time, reproductive cells, which are larger than regular egg laying cells, are constructed. These reproductive cells house the next year's queens. As the cooler fall air arrives, the queens leaves the colony in order to find a location in which to overwinter. Except for the overwintering queens, the colony will die once winter begins.

Diet:

Yellow jackets generally feed on insects, fruit, carrion (the flesh of a dead animal), nectar, and when given the chance, processed food and drinks for humans. While adult yellow jackets feed exclusively on nectar and fruit juices, they gather insects, arthropods, carrion to feed to larvae. Yellow jackets do not sting live prey for the larvae; rather, they use their powerful jaws to capture and kill it.

Those species of yellow jackets are attracted to human food are considered pests because of their aggressive behavior and readiness to sting. These yellow jackets will search through trash containers and forage on picnic tables. Unfortunately, they do not distinguish between food in a trash can and food held by a person. They will become aggressive when someone attempts to shield or protect food from them. They are quick to sting or use their mandibles to bite in order to defend themselves and their food.

Concern for Humans:

Beyond being an annoyance at outdoor gatherings, yellow jackets can actually pose a significant threat to some people. Annually, over 500,000 people a year seek emergency room treatment due to stings from yellow jackets and other stinging insects. About 3% of the population has a severe, systemic reaction to bees and wasps. Even  one sting, if not properly treated, could be fatal. According to the American College of Allergy, Asthma, and Immunology, there are three types of reactions to yellow jacket stings. First, is a normal local reaction in which a person suffers from pain, swelling, and redness directly around the site of the sting. Second, is a large local reaction in which there is swelling well beyond the site of the sting. For example, a large local reaction would be a sting on an ankle that causes a whole leg to swell and stay swollen from a few days up to a week. The third reaction is the most serious, a systemic allergic reaction. This potentially life-threatening reaction people requires medical intervention. Symptoms can range from mild to severe, including hives, itchiness, swelling in areas away from the sting, dizziness or a sharp drop in blood pressure, swelling of the tongue or difficulty swallowing, abdominal cramping, vomiting, intense nausea, diarrhea, unconsciousness, or cardiac arrest. Anyone with a known systemic allergic reaction to yellow jackets or other insect stings should carry an EpiPen (an epinephrine auto-injector) with them in the event of a sting.

Conservation Status:

Yellow jackets are not endangered. However, there is some concern that certain non-native species of yellow jackets will force native yellow jackets from their current locations. Recently there has been an influx of German yellow jackets into North America. German yellow jackets are significantly more aggressive than native yellow jackets like the Eastern yellow jacket.

Ways to Avoid Yellow Jackets:

The most effective way to reduce the number of yellow jackets around a home or public places such as parks and playgrounds is if everyone makes a conscious effort to reduce the amount of food available to them. Reducing food availability directly reduces yellow jacket populations. Workers will spend more time and energy foraging, leaving less time for them to help develop larvae, and the size of the colony will be reduced. In parks and public areas, be vigilant about removing trash and recyclables promptly, and if food is thrown away, use receptacles with lids. Take similar precautions around your home with outdoor events. Keep food covered and never leave out ripe fruit or cans with sugary sodas. Finally, don’t give yellow jackets the mistaken impression that you are food. Wearing sweet-smelling perfumes is asking for trouble.

Removing Yellow Jacket Nests:

NJ Homeowners Guide to Yellow Jackets - Image 2

Removing yellow jacket nests is not a good DIY project. A horde of agitated wasps is not somethingyou want to deal with on your own. With yellow jacket nest removal, hiring a pest control professional with the right chemicals and protective equipment is the way to go. A pest control professional will make sure that the job is done right: all the wasps are dead, and the nest is removed. Let the technician assume the risk of dangerous stings instead of you or your family. Often, in hindsight, homeowners who try to deal with yellow jacket nests on their own spend more money on medical bills later. Please don’t let the intense pain of yellow jacket stings serve as a reminder that some projects are best handled by licensed professionals.