The term "yellowjacket" is applied to most social wasps in the US. Yellowjackets belong to the order Hymenoptera, indicating that they are social insects, and are in the family Vespidae, indicating that they construct their nests from paper. There are 19 species in North America, but among those which tend to become the largest pests are three species, all of which are common to Indiana. These are the Eastern yellowjacket (Vespula maculifrons), the Southern yellowjacket (Vespula squamosa), and the German yellowjacket (Vespula germanica). These three species are ground nesters most of the time, but may nest in protected voids on structures as well. Their habits are similar.

In the spring, queens emerge from the protective hiding places where they diapaused and search for suitable nest sites. After locating a site, such as an old rodent den or a void under tree roots, she constructs a small nest out of paper, which she forms by mixing chewed wood with her saliva. The queen then lays eggs within cells in the nest. She feeds the developing larvae chewed insects, and nectar or sap from plants. These larvae pupate, emerging as sterile adult females which take over the work of foraging for food and fiber, feeding successive larvae, and expanding the nest and the nest void. Toward the end of the season, there may be as many as 5000 individuals in a yellowjacket colony. With the approach of autumn, the queen lays eggs which become males and fertile females. She then dies.

The males and new queens emerge and fly off to mate with emerging yellowjackets from other colonies. After mating, the males die and the newly inseminated queens seek a protected place in which to diapause. The remaining workers will continue to forage so long as the weather is warm, but die off with cooler temperatures. The next spring the entire cycle starts anew. In some southern states where a freeze is rare, colonies will continue to grow with newly mated queens taking the place of dying queens, but in Indiana a queen must always start her colony from scratch.

Yellowjackets come into conflict with humans through their foraging activities, or when they build their nests in, on, or around human structures. Workers forage for protein and sweets, and are attracted to dumpsters and garbage cans in search of soda residue, ripe fruit, candy wrappers, meats, or other insects to feed themselves and larvae in the nest. Although yellowjackets can be considered beneficial by keeping the numbers of other pests low, when foraging brings them to schools and childcare centers, they themselves become pests. They create the greatest problem in the late summer and early fall when colonies are large, and there are a great number of foraging workers.

Whenever yellowjackets are in close proximity with people, there is a good chance that someone could be stung. For this reason, many people are afraid of yellowjackets. In addition, between 0.5-1.0% of the population is highly allergic to yellowjacket venom. Yellowjackets will defend themselves and their colonies aggressively. The Southern yellowjacket even has an alarm pheromone which will prompt a vigorous attack and stinging by multiple individuals. Due to the danger posed by foraging yellowjackets, foraging around schools and childcare centers must be controlled. If food is found, a yellowjacket will return to that same site. If the site yields success a second time, it will return with its nest mates.

Effective control depends largely upon strict sanitation, and exclusion of yellowjackets from food sources. The proper disposal of garbage is essential. Trash containers should be kept indoors if possible. All containers should have tight-fitting lids, and be emptied frequently. Dumpsters and other trash containers that do not have removable liners need to be cleaned or rinsed frequently. All garbage receptacles should be placed in areas of low human activity. Recycling should be kept in large plastic bags which are tied shut, or in some other type of sealed container, and care should be taken to avoid any spillage on or around the recycling storage area. Spills, especially of sweet, sugary, or syrupy substances, need to be cleaned immediately. In addition, seal wall penetrations and screen vents to prevent the entry of yellowjackets into the building.

If a nest is discovered in the vicinity of the school or center, it should be reported immediately to the administration and the IPM Coordinator. Staff should not immediately attempt to remove the nest. The IPM Coordinator will take action to remove it at night when there is little danger to children and staff. If staff can identify the location of the nest, it should be marked with hazard tape. Give the nest a wide berth when erecting a hazard tape barrier.

If there are yellowjacket foragers inside the building, try to ignore them. Yellowjackets have a photopositive response, and will ultimately settle by a window or find their way back outside. If there is a yellowjacket inside which cannot be ignored, then it should be killed, but only as a last resort. A bungled attempt will make it angry, creating a larger problem.

If a child is stung, s/he should immediately be brought to the school or center health practitioner, and a parent or guardian should be contacted for allergy information. If a person is stung and exhibits an allergic response, or is known to be allergic, medical attention should be sought immediately by calling 911.

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