It’s no secret that most of us try and duck out of sight whenever bees get too close. Even though we are quick to realize they are necessary pollinators for many of our flowers and vegetable crops, we still prefer to avoid close encounters with any insect that resembles a yellow jacket. Not all bees are as undesirable as yellow jackets, however.
The European paper wasp (Polistes dominulus) is now appearing throughout our coastal area and this insect has a voracious appetite for aphids and other common garden insects. They feed solely on insects and, as a result, bring excellent early-season biological control to many pests.
European paper wasps have markings similar to the typical yellow jacket and the two are often confused. They both have black and yellow warning coloration striped along their bodies.
One superficial way to tell the difference is noting the body shape. Paper wasps in general are more slender and have longer legs. The constriction from the abdomen to the thorax is more gradual for paper wasps, while the constriction of the waist on yellow jackets tends to be abrupt.
Those who don’t care to get close enough to make these observations can also tell the difference between the two by simply observing nesting habits.
Paper wasps create nests that are only one cell deep, forming a single comb and resembling an upside down umbrella. The comb is not enclosed and is exposed to the outside world.
European paper wasps find human structures a favorable place to establish their nests. It is not unusual to see multiple nests beneath roof eaves and overhangs, birdhouses and even mailboxes.
Yellow jackets, on the other hand, create large aerial nests that are entirely enclosed in paper. Yellow jackets will also construct nests below the soil surface.
Female paper wasps over-winter as fertile adults in protected areas such as under tree bark, woodpiles and inside walls of structures. Females become active in early spring. Over-wintering females can colonize an existing nest from the previous year, or construct a new nest made from chewed and pulped wood fiber.
All paper wasps are social, forming colonies headed by a queen, but the Europeans take this trait to the extreme. They’re so social, that they’ll have two different queens in the same nest, helping each other out, contrary to most domestic wasps. Queens deposit eggs singly into individual cells.
These cells are home for the wasp larvae until they reach adulthood. The queen hunts and brings back prey items, such as caterpillars, and macerates the prey to feed to the larvae. The first brood can hatch to adults within 40 days, given good environmental conditions.
After the first brood, the queen continues to reproduce while the newly emerged workers take on the duties of foraging and maintaining the nest.
Although nests can grow to 400 cells, most nests contain fewer than 100 cells. Male wasps are produced late in the season and mate with next season’s new queens. The fertilized females seek out over-wintering shelters to begin the lifecycle for the following year.
There is documentation in other parts of the country that paper wasps can inflict painful stings when disturbed, and are capable of stinging multiple times. In the Eastern United States, the species is labeled as a fierce defender of nests and will attack potential threats.
So far, however, the European paper wasp has been described as docile in the Pacific Northwest. It most often will give you a “courtesy bump” telling you to back off before it threatens to sting you.
If possible, leave European paper wasp nests alone. You will benefit from having these voracious predators working for you in your garden and landscape. In general, these wasps have brought excellent early-season biological control of many pests in our coastal area. There are not many natural enemies of insect pests that are active in early spring, so that makes the European paper wasp all the more welcome.