If you thought swarm traps were for honey bees

Think again. The elegant and complex nests shown below were built this summer in two of my three swarm traps. I’ve been using the same three flowerpot-shaped traps for perhaps ten years, hanging them each year from the same three trees. In early spring, we go trudging up the hill with a ladder and the traps, each outfitted with a fresh swarm lure. Some years I catch multiple swarms, sometimes nothing, but I’ve never before caught yellowjackets.

Hijacking a swarm trap

I was surprised when I found the first nest but floored to find the second. What changed, I wondered. We always have yellowjackets here, as well as bald-faced hornets, but I usually find their nests swinging from the branches of a tree.

My honey bees were not bothered by yellowjackets this year, although the bald-faced hornets were a nuisance. Unfortunately, I only discovered the bald-faced hornet nest late in the year, right above my head, hidden in the leaves of a pear tree.

Aerial yellowjackets and bald-faced hornets

Just to clarify, this type of wasp is known as an aerial yellowjacket, Dolichovespula arenaria. They go by several other common names including yellow hornet and sandhills hornet, and are in the same genus as the bald-faced hornet, Dolichovespula maculata. Unlike these tree-dwellers, most yellowjackets are in the genus Vespula and build their nests in the ground.

In previous years I often saw yellowjackets pestering my bees and trying to get inside the hive. But this year I added robbing screens early and, in spite of all the ‘jackets in the apiary, I had no trouble with them. The most irritating thing was their constant scritching on my wooden tomato ladders and fence posts. When I worked in the garden, I could hear them scraping the fibers from the boards, and if I looked carefully, I could see where they had gnawed into new wood. I’m surprised there was enough left to support the vines.

Saliva and wood fibers

The wasps mix the wood fibers with saliva to build their nests. The nest coverings are marbled with various colors of wood which intermingle in artistic swirls. Although they look firm in the photo, the layers are so soft and flexible they are hard to handle.

Once the wasps were gone for the season, we brought the traps down to the house. With a large knife, I cut a nest from the inside wall of the trap. At the far end is the entrance hole where the wasps come and go. These wasps would have exited into the dark interior of the swarm trap and then proceeded through the swarm trap entrance. Double doors! The swarm traps provided security against wind, rain, predators, thrashing limbs, and birds.

Even though I discovered these nests early and wrote about them back in June, I let them stay because I thought they’d be fun to dissect. They certainly lived up to that promise. I found only one wasp inside, a queen, and I believed she was dead. I photographed her before lunch, but when I came back a half-hour later, she was gone. Not quite as dead as I thought.

Hexagonal cells made of fiber

After I photographed the outside, I slit the multilayered covering. This particular nest has eight combs, including two very small ones at the ends. Each comb is circular and hangs parallel to its neighbors. The cells are roughly hexagonal and seem to made of the same material as the outer covering, except denser and more rigid. The entire structure, combs and covering together, is light as a feather and would easily blow away. It’s amazing these structures last through an entire summer.

In case you forgot how closely related the honey bee is to the social wasp, these photos will remind you. The resemblance is uncanny, and it makes me think that when a yellowjacket invades a honey bee hive, she already knows her way around.

Rusty
Honey Bee Suite