When yellowjacket traps don’t work

A reader from Oregon wrote to say his purchased yellowjacket traps did nothing to stop yellowjackets. A northern California reader said she left the traps hanging all spring and summer and captured one yellowjacket, even though she could see them flying all around her garden and beehives. What gives?

The problem is usually one of mistaken identity. Although we refer to most yellow-and-black waspy-looking things as “yellowjackets,” the reality is more complex.

The first thing to remember is wasps, yellowjackets, and hornets are all wasps. They may be different species or different genera, but they all fall into the wasp group. The second thing of note is that a “yellow jacket” (two words) is an outerwear garment made from yellow fabric—a different topic altogether. I have both.

Most yellowjackets are in the genus Vespula. Usually, these live in underground cavities and can deliver a series of nasty stings. They are difficult to distinguish from one another, but if you’re inclined, the pattern of stripes on the abdomen can give you clues to their identity.

Aerial yellowjackets

However, one common yellowjacket is in a different genus. This species does not live underground; instead, it builds a large bulbous paper nest in a tree. If no trees are available, as in some urban areas, this wasp will build its paper nest on the side of a building.

These tree-nesters are commonly called aerial yellowjackets since they nest in the air, not underground. Aerial yellowjackets are in the genus Dolichovespula, along with a close relative, the bald-faced hornet.

Bald-faced hornets

Most North Americans have run into a bald-faced hornet (Dolichovespula maculata) at least once. These wasps are widespread in Canada and the US, especially on the west coast, in the Rocky Mountains, and throughout the eastern and southeastern states. Bold black-and-white markings, including a white patch on the face, give them their common name. You may also hear them called blackjackets, white-faced hornets, or spruce wasps.

Like the aerial yellowjacket (Dolichovespula arenaria), bald-faced hornets live in trees. They build large paper nests by chewing wood into a pulp with saliva and then gluing it in place. The nest can be huge, with 400–700 workers. Their populations build throughout the season, with the maximum number occurring in July through October. They love nothing more than a delicious meal of honey bees to serve their young.

Paper wasps

To add to the confusion, paper wasps are also mistaken for yellowjackets, especially the yellow and black ones such as the golden paper wasp and the European paper wasps. Paper wasps are in yet another genus, Polistes. They build “umbrella nests” that are much smaller than the nests of Dolichovespula, and they have a stalk that makes them look like an inverted umbrella. The nests often hang from porch ceilings and eaves.

Although they, too, are predators of other insects, the smaller nests house fewer individuals. Polistes have long legs that dangle below their bodies as they fly, making them easy to identify.

What’s in the yellowjacket trap?

Pheromones are often used to bait the commercial traps. But many traps that are labeled to catch “yellowjackets” are designed to lure insects in the genus Vespula. Vespula, as you now know, does not include paper wasps, aerial yellowjackets, or bald-faced hornets.

When you want to capture these others, you must look for traps that specifically list them. Remember, pheromones are very specific: they are not one-size-fits-all. Traps for these others exist, but you need to 1) figure out which insects you have and then 2) look for them on the label.

Alternatives

Personally, I have found that nothing catches a broad spectrum of wasps like brown sugar and water. Others like to make meat traps or yeast traps. It’s up to you, but it always helps to know what you have before you try to get rid of it.

Rusty
Honey Bee Suite

Note: The top image shows a group of bald-faced hornets at their nest in my backyard.

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