It's Yellow Jacket Time

Yellow Jacket entering its nest.
Yellow jacket entering its nest/Terry W. Johnson


By Terry W. Johnson

The yellow jacket is one of our most reviled insects. In fact, I can safely say I personally do not know anybody who has a kind word to say about these small, half-inch-long yellow and black wasps. However, it seems that folks most often talk about their dislike for yellow jackets in the summer and fall. I suppose this is because we seem to encounter this annoying, stinging insect more during these seasons.

For weeks, yellow jackets have seemed to be everywhere. If we go on a picnic, they quickly swarm the food and beverages that otherwise make this event so special. The simple act of changing the nectar in a hummingbird feeder becomes a dangerous proposition when the feeder is covered with yellow jackets. During hunting season, they invade our campsites and can make cleaning a deer or other game a challenge.

Yellow jackets are predators and scavengers. They forage for foods packed with carbohydrates and sugar. The items they’ll eat include tree sap, nectar and the juice of fruits and berries  Since the insect is fond of sugary foods, it rarely misses the chance to sample our soft drinks and food. For that reason, before you take a bite when eating outdoors, it’s wise to make sure one is not dining on the backside of your egg salad sandwich. Similarly, before you raise a soda can to your lips, make sure a yellow jacket has not crawled inside to sample your sugary sweet drink.

Throughout most of the summer, yellow jackets spend much of their time hunting spiders, caterpillars, flies and other invertebrates. It has been estimated that yellow jackets are capable of capturing more than 2 pounds of insects from a 2,000-square-foot garden plot. This member of the wasp family also scavenges everything from dead worms and insects to road-killed animals and other carrion.

The yellow jacket is a social insect that lives in colonies consisting of a queen, infertile female workers and males. The queen is much larger than the other colony members, reaching about three-quarters of an inch in length. She is also the only member of the colony that is capable of overwintering.

Once the queen emerges from her winter sanctuary, her first task is to find a suitable place to establish a nest. Most often, she selects an abandoned rodent burrow or other hole in the ground. Occasionally, yellow jackets will also nest in buildings, abandoned vehicles and hollow trees. Often the potential nesting sites are in our gardens or around tree trunks and the like.

Once a site is selected, the queen chews up bits of wood to the consistency of wood pulp and uses it to build a small nest. When dry the nest looks as if its fashioned from thick paper. She then begins laying eggs, which hatch into infertile female workers in about three weeks. For the rest of her life, the queen remains in the nest laying eggs. The workers are responsible for expanding the nest, providing food for her and her young, and defending the colony.

By the end of the summer, a typical nest will be roughly the size and shape of a football and house up to 800 yellow jackets or more. (An astounding 250,000 occupied one large nest found near Charleston, S.C.)

Most of us are well aware that yellow jackets will vigorously defend their nests and sting when provoked. During an attack, a yellowjacket can sting multiple times without losing its stinger. In addition, when it feels threatened, the insect releases something called an alarm pheromone. When other yellow jackets detect the chemical they immediately become aggressive and join the attack.

For the most part, yellow jackets will not attack unless they are antagonized or we venture too close to a colony.  However, late in the summer folks seem to be stung more often than at any other time of the year. This may be because yellow jackets are more abundant. However, they also become less tolerant of one another and seem more prone to sting without provocation. Since this behavioral change coincides with a switch from a predominantly protein diet to one rich in carbohydrates and sugars, some suggest this may affect their aggressive fall behavior.

All while this is taking place, new queens and males are hatching in nests scattered across the countryside. Soon the young queens will begin storing the fat that will sustain them throughout the coming winter. Eventually they will reach the point where they abandon their nest and are pursued by the males. Once mating takes place, the males die and the fertile queens search for suitable winter quarters such as a hollow tree or beneath the bark of a tree.

Back at the nest, the number of workers slowly dwindles. With the onset of cold weather, the workers and the old queen die and the nest begins to deteriorate. The once vibrant hub of activity will probably never be used again.

In spite of its obnoxious behavior, yellow jackets do have some redeeming values. Remarkably, mammals such as bears and skunks dig up the nests and devour the juicy young. Yellow jackets also eat a number of insect pests that plague ornamental and agricultural plants. In addition, while collecting nectar, they play a small role in pollination.  Native Americans even once used yellow jackets to prepare a soup.

It is clear that the yellow jacket will never win a nature popularity contest. But perhaps researchers will one day discover some unknown value to this stinging insect. In the meantime, perhaps the best thing for us to do is just stay out of its way.

Terry W. Johnson is a retired Nongame program manager with the Wildlife Resources Division and executive director of The Environmental Resources Network, or TERN, friends group of the division’s Nongame Conservation Section. (Permission is required to reprint this column.) Learn more about TERN, see previous “Out My Backdoor” columns, read Terry’s Backyard Wildlife Connection blog and check out his latest book, “A Journey of Discovery: Monroe County Outdoors.