European Paper Wasp

Human activity and travel around the world have managed to transport more than just people from place to place. We also have done a very thorough job of relocating a lot of living animals and plants, sometimes with devastating results. In fact, a very large percentage of the common pest animals in the United States are “exotics”, having their natural habitat in some other part of the world. Among these imported problems we find some that you might not realize are exotic invaders, since they have been in North America for so long. Examples include pigeons, starlings, Norway Rats, the House Mouse, earwigs, three or four of our most common cockroach pests, Argentine ants and Red Imported Fire Ants. In fact, even our beloved “native” honeybee is not native at all, having been brought to North America by some of the first European immigrants. The list of exotic imports also includes a phenomenal percentage of the plants you see along roadsides and in your landscape.

One of the newer exotic imports is a wasp, and it has spread rapidly across the United States after being discovered in Massachusetts around 1980. By 1998 it was being found in California, and now the University of California reports that it rapidly is becoming the most common paper wasp found throughout the state. Unfortunately this may be at the expense of other, truly native paper wasps. The European Paper Wasp – whose scientific name is Polistes dominulus, tends to come out of winter hibernation earlier in the spring, and by aggressively foraging for food and nesting sites it may be displacing other kinds of paper wasps. The new species also will happily make its nests around human activities and our dwellings, and seem to have a particular fondness for nesting under the tiles of Spanish Tile roofs, making their control extremely difficult.

Paper wasps are in a family of wasps that is given the scientific name of Vespidae, and another well known group of wasps in this same family is our yellowjackets, which we often hear referred to as “meat bees”, due to the tendency for several of the species to try to share our hot dogs and hamburgers when we are eating outdoors. Paper wasps and yellowjackets are all social insects, creating a nest and organized colony, with a queen to lay the eggs and workers that care for the growing larvae and forage for food for the colony. The food of the larvae, as it turns out, is meat, and in the absence of humans and our own foods that meat will be natural sources such as other insects or carcasses of dead animals. Caterpillars are a particularly good source of meat, and in this respect these insects provide some benefit to us. However, yellowjackets and paper wasps also can sting, and in defense of their nests will readily go after people or pets that stray too close for them.

The European Paper Wasp looks very much like a yellowjacket, and could easily be confused with one. It is the same black and yellow color with very similar markings, but with a much more slender abdomen and somewhat narrower waist area. The nests of paper wasps also are different from those of yellowjackets. Both kinds of wasps create their nest by using dried plant materials, such as bark from trees, dried flower stems, etc., working this into a mushy paper mache that they can then form into the rather beautiful nests with cells, where their larvae will live and grow. Yellowjackets nearly always enclose the nest with an outer shell, and their colonies can become extremely large, upwards of 25,000 wasps by the end of the summer if they have done well. Neither paper wasps nor yellowjackets continue the colony through the winter in areas where it gets cold, so all that work starts from scratch with a new queen creating a new colony in the spring.

Paper wasps have much smaller colonies, with some of the largest getting only to about 100 workers in a nest. Rather than enclosing the nest they create it with the cells exposed and the nest hanging upside down, suspended on a thin stalk. The general appearance of this design gives rise to another name for these insects, which is “umbrella wasps”. That nest commonly is attached to the surfaces under the eaves of your home, within bushes, under the horizontal boards on your fence, within the garage or the attic, under or within motor homes or boats, inside light fixtures, and just about anyplace else these opportunistic insects can find that is secure and somewhat out of the way. Some species will even coat that stalk with a chemical that acts as an insect repellent, effectively keeping marauding ants from going after the eggs or larvae in the nest.

The paper wasps are not scavengers, and you will not find them trying to pick bits of food off your hamburger, nor entering a can of soda to drink the sugary fluids in the manner that yellowjackets do. Instead, they stick with natural foods, and the European Paper Wasp is particularly fond of small caterpillars. While we generally might welcome this behavior, when it comes to picking pest caterpillars off our garden plants, we need to recognize that the wasp is not picky in its choice of caterpillars, and only time will tell if the many native butterflies and moths are at risk. Some surveys done in Kansas and Colorado already are suggesting that this wasp may be responsible for the apparent near lack of butterflies in some areas by the middle of the summer.

There already is a growing opinion among wasp experts that other, native species of paper wasps are rapidly disappearing from areas where they once were common. The hibernating queens of the European species emerge earlier in the spring, begin their nest building earlier, and thus are foraging for available food resources earlier than native species. The nests are commonly built in smaller cavities, such as under the tiles of roofs, in barbecue grills, in bird houses, or in attics, and this keeps them from exposure to predators that might keep them in check.

Controlling umbrella wasps is relatively easy to do if you can locate the nest itself. Aerosols that direct a stream of spray up to about 12 feet away can quickly dispatch the wasps resting on the nest, and this should be done in the evening when the wasps are not active. It may be most appropriate to leave this up to a licensed pest control company, as they have the products to perform this as well as any protective clothing necessary to keep from being stung. One thing to keep in mind is that the paper wasps will not be attracted to the traps used for capturing yellowjackets. This is one more reason that proper identification is important. If you suspect that a nest of these wasps may be in a place you need to be care must be taken not to get too close. The wasps are very willing to go after and sting any intruder they consider a threat to their colony.

You can help to limit the number of nest sites for these wasps by closing off unnecessary openings in the outside of the home, such as under the eaves or where pipes and cables penetrate the walls. Make sure screens are in place for the attics or crawl spaces under the home, and of course make sure that windows are properly screened and doors kept closed to prevent their entry into the home.