Yellowjackets 14
Bonifacia Cramm
Yellowjackets are a very common summer and fall pest in the United States, and while they are grouped in the general category of stinging insects, yellowjackets have some pretty unique characteristics. Understanding what sets yellowjackets apart is the first step in controlling them on your property and reducing the likelihood of stings.
Like many other flying insects, adult yellowjackets feed on sugary substances such as flower nectar, fruit, and the occasional soda when they find an open can. What makes yellowjackets unique is that they consume protein in their larval stage. Workers bring insects and other types of meat back to the nest as food for the larvae. Most homeowners consider yellowjackets a pest, but their diet actually makes them an important part of garden pest control.
Yellowjackets are normally very slow to sting, but they are also very territorial. If the entrance to their nest is approached, they will become very aggressive. They can sting multiple times, and their stings can be very painful. People who are allergic to their venom could have a severe reaction, and it is possible to become hypersensitive to yellowjackets after being stung. This sensitivity could cause a serious problem if stung again in the future.
A typical yellowjacket worker is about -inch long with alternating black and yellow bands on the abdomen (the black and yellow patterns on the abdomen help separate various species). Queens are visibly larger, approximately -inch long. The larvae within the nests are white and grub-like. Workers are often confused with honey bees; however honey bees are covered with dense hair and have flattened hairy hind legs used to carry pollen, while yellowjackets have hard, shiny, mostly hairless bodies. Wasps and hornets tend to fold their wings lengthwise while at rest and fly with their legs close to their bodies, while honey bees often fan their wings out slightly while feeding. Mouthparts of yellowjackets are well-developed for capturing and chewing insects with a tongue for sucking nectar, fruit, and other juices.
Nests are typically built in animal burrows, cavities formed in thick mulch piles, or other protected cavities such as rotted tree trunks, wall voids, and ceilings. Nests are constructed entirely of wood fiber mixed with wasp saliva and are completely enclosed, except for a small opening at the bottom. The nest contains many tiers of combs, sometimes 10 or more. Nests built in the open are usually constructed by bald-faced or yellow hornets, which have similar life cycles and habits of yellowjackets.
There are several commercial non-toxic bait traps available for yellowjacket wasp control. It is important to know that no trap provides rapid knockdown of yellowjacket populations. For effective use, traps should be placed outdoors two or more days prior to the event. Keep in mind that most commercial traps are not attractive to German yellowjackets, which are the most common nuisances in Ohio.
Many insecticides are labeled for control. "Restricted Use Pesticides" can only be applied by a licensed pesticide applicator or trained service person. Control of social wasps (yellowjackets), although usually not difficult, has its element of risk of being stung. Because most foraging has ceased by sundown, it is best to attempt nest removal at early dawn because they are slow and sluggish after enduring the night's cooler temperatures. Never shine a flashlight at the entrance of any bee or wasp nest, as they will fly toward the source of light. If applications must be made during the day, the use of protective equipment, such as gloves, hat, bee veil, coveralls, etc., will prevent stings from any foraging wasps. Goggles are recommended as the workers are known to squirt venom at animal eyes. It is highly recommended to hire a professional to kill and remove wasp nests!
The District provides inspection and treatment of ground-nesting yellowjackets since these species are aggressive toward people. We do not provide a service for other species of yellowjackets, nor those that make their nest on or in structures.
Ground-nesting yellowjackets construct paper nests that may contain thousands of larvae and adult workers. These nests are typically located underground in abandoned rodent burrows or in other enclosed spaces such as tree cavities, wall cavities, wood piles, and dense ivy. During the fall, young queens mate and find protected areas (such as fallen logs, tree cavities, cracks in buildings, etc.) where they remain for the duration of the winter. When spring arrives, queens select nesting sites and begin the process of colony initiation (nest construction, deposition of eggs, and hunting for food). Once adult workers emerge, they take over many of the tasks of nest maintenance so that the queen can remain within the safety of the nest and lay eggs. Foraging ground-nesting yellowjacket workers commonly come into contact with people who are eating outdoors and may become extremely aggressive. The colony grows throughout the summer and into fall, and eventually begins production of males and queens. When rain and/or freezing temperatures return, nests typically die out, and newly mated queens find protected areas to overwinter so the process can begin anew in the spring.
Yellowjackets and other wasp species do not use the same nest again the following year. New queens start a new nest each spring; although a favorable nest site maybe chosen year after year if adequate space is available. New queens, which are the only members of the colony that survive the winter, do not overwinter in the nest. They leave the nest in the fall and overwinter under tree bark and other protected sites. The workers usually die out by the first of November. The best method of controlling yellowjackets is to locate the nest and treat it with a registered insecticide. Hornet and Wasp sprays are effective in killing individual wasps and much like shooting skeet, they also provide a certain amount of recreation. However, serious wasp control requires that the nest be located and treated directly.
Often mistaken for honeybees, yellowjackets are brighter in color, with a thinner, more defined waist. Visit our blog for more differences between yellowjackets and honeybees.
Yellowjacket nests are made of paper like those of paper wasps, but they have multiple parallel layers of comb with downward-facing cells (paper wasps always only have a single layer of cells). Yellowjacket nests are always enclosed in a wood-pulp paper envelope built by the wasps. They are most typically constructed underground, and all most people ever see of a nest is the entrance hole with yellowjackets flying in and out of it.
Similar species: Missouri has many wasps that could be confused with yellowjackets (genus Vespula). Indeed, some people call yellowjackets "ground bees," confusing them with bees, which is another whole group in the ants/bees/wasps order. There are also several types of flies, beetles, and other insects that mimic wasps, too. But here are some of the most common yellowjacket lookalikes:
Though yellowjackets may have constructed a large paper nest beneath the soil, all you might see is a simple-looking hole in the ground, with wasps flying in and out of it. This is something to watch for if you are out in your yard or are preparing to mow.
As the summer progresses, nests increase in size and in the numbers of wasps they hold, becoming more conspicuous. In late summer, when their nests are at their highest populations and as natural food sources begin to dwindle, yellowjackets are more likely to visit soda cans and garbage containers, and they might be simply more irritable, too.
Because these are social, not solitary wasps, yellowjackets are willing to protect their family's colony with aggressive stinging. This is one of the wasp genera that can, as groups, chase and sting an intruder who stumbles upon their nests, including people and pets.
Many people encounter yellowjacket nests when they are mowing a lawn and fail to notice the wasps flying in and out of the hole in the ground that is the entrance to their nest burrow. Before mowing, it's always a good idea to walk the area to look for rocks, sticks, trash, and the nests of animals (including yellowjackets).
If yellowjackets seem unreasonably "mean," remember that they are defending their home and family from what their brains perceive as potential destruction. Many of us are prepared to do basically the same thing, on a personal and even a national level.
People rightly fear yellowjackets and other social wasps that are capable of stinging en masse. But as with many animals that can powerfully affect humans, these wasps have earned a place of respect in our culture. Note, for instance, the many sports teams that are named "yellowjackets," "hornets," and so forth. Proud Missouri high school yellowjackets include Center High School (Kansas City), Glasgow, and Lebanon. Proud Missouri high school hornets include Advance, Chillicothe, Craig, Crystal City, Fulton, Hillcrest (Springfield), Laquey, North Kansas City, Penney (Hamilton), and Westran (Huntsville).
The black-and-yellow striped pattern of yellowjackets warns predators not to mess with them. The coloration is easily memorized by animals after being stung. Once educated, those animals learn to avoid the wasps. It's a win-win for the yellowjackets and for the animals that have learned the painful lesson.
Skunks, raccoons, badgers, bears, and other mammals have been known to attack and destroy yellowjacket nests in order to eat the wasp grubs, eggs, and even adults. Skunks typically attack at night when the yellowjackets are least active, digging into the burrow, pawing through the nest, and eating the wasp larvae. If you find that skunks have been pawing holes into your yard at night, they might be saving you from a nest of yellowjackets in your lawn.
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