Lessons from the year of the wasp

Wasps can be a problem for beekeepers in the autumn of the year. In fact, we usually don’t think about wasps at all until they begin casing our hives, looking for fresh meat. The biggest threat comes from eusocial species—those that are “truly social,” like yellowjackets.

In all but the warmest regions of North America, mated female wasps overwinter alone and begin nesting in the spring. In solitary species, the female builds a nest of her own, but in eusocial species, overwintered queens begin a whole new colony.

Because the eusocial species begin their colonies from scratch each year, you see few of them in the early spring. The ones you do see are usually queens, big and fat. Then, as the season progresses, the colony gets bigger and bigger. By fall, eusocial wasps can be a threat to honey bee colonies because all those hungry critters are looking for food. A hive of nice tender honey bees, all gathered in one place like a fast-food restaurant, is a mouth-watering treat for hungry wasps.

Each year I catch wasps—usually bald-faced hornets—as they stake out the hive entrances, darting and weaving among the returning bees until they manage to knock one out of the air. As the stunned bee hits the ground, a hornet dives in and scoops it up. Bee hives make the hunting easy.

Wasps and more wasps

As routine as wasps are, this year was different. Where I live, it seems like wasps have completely usurped the wild bee populations. Each time I went out with a camera to take pollinator portraits, all I found was wasps. Not just social ones, but solitary ones too. Some of the insects I thought were bees at first glance, turned out to be wasps I’ve never seen before.

While I have plenty of the usual aerial yellowjackets and bald-faced hornets, my place is teeming with little ground-nesting yellowjacket-like wasps. Oddly, I keep mistaking them for bees. They trail me around the yard, fly into me like head-butting honey bees, and if I’m eating anything, they do their best to get a bite.

I haven’t actually found their homes, but I’ve zeroed in on a few likely spots. I think there’s a nest under the azaleas and one under the hop vines. The raspberries vines, too, shimmer with them. When I get near those places, stripey creatures with wings threaten me with nervous side-to-side aerobatics.

My pollinator gardens, which are usually loaded with solitary bees, have been overtaken by wasps of every description. Big and little. Red and yellow and black. Friendly and not so much. Believe me, they are everywhere.

A bee and wasp survey

Quite by coincidence, I’ve been assisting with a bee and wasp survey for a government agency. I have established several locations, each with three different types of trap—two bee traps and one wasp trap. All the traps are baited with brown sugar syrup, some with yeast and some not.

When I first installed the traps, I was terrified of catching honey bees. Three of the traps in particular are very close to my own hives, and I had mental images of entire colonies of honey bees stuffing themselves into the jugs and drowning. The first day or so, I checked the traps every few minutes for honey bees, intending to change locations if honey bees began to accumulate.

Lesson one

After the first two weeks, I stopped worrying about it. In fact, since May, I’ve found only five honey bees in all my traps combined. Our summer dearth began right on schedule—about July 1—and still no honey bees entered the traps. So that’s lesson one: honey bees are not interested in plastic jugs of brown sugar syrup.

But wasps? Never in my life have I seen so many wasps. Each week, the traps are loaded—I mean overflowing—with our most common social wasps, aerial yellowjackets (Dolichovespula arenaria) and bald-faced hornets (Dolichovespula maculata). When I empty the traps, great heaps of these things clump into the strainer. It doesn’t matter whether it’s a bee trap or wasp trap, with yeast or without.

It’s actually kind of disgusting. I rinse these things off with water and use forceps to drop them in bottles of alcohol. I look for bees as I go, just to satisfy my own curiosity, but everything insecty-looking goes into the alcohol. So far, I’ve seen very few bees of any type, which isn’t surprising since my garden is without solitary bees as well.

Cartoon bees

The two species of eusocial wasps in the traps, both in the same genus, are the kind that build large, gray, balloon-shaped nests that hang from trees and swing sets. They’re the ones cartoonists draw as “bee hives”—hanging sweetly from a tree and surrounded by smiling yellow-and-black bumble bee-like creatures.

It’s all a lie. These insects are skilled hunters that can be vicious, if you’ll excuse the anthropomorphic description. Worse, they can overcome a honey bee colony in no time. I can’t say I was sad to see them all matted together in sticky clumps, and the sight of them led me to lesson two.

Lesson two

I compared the number of wasps in my brown sugar traps to the number of wasps in the commercial yellowjacket traps I use every year. The commercial traps, even with fresh (and expensive) lures caught fewer wasps all summer than one brown sugar trap caught in a week. So why not use brown sugar traps to safeguard honey bee hives?

It’s an odd thought because I always assumed that a sugar trap of any type would attract honey bees, but that has just not happened, even during nectar death. And this year, as bad as the wasps have been, only one of my hives—the one furthest from the traps—has been pestered by bald-faced hornets.

Further experimentation

I’m not recommending you run out and try this, but I think it’s an idea worthy of more experimentation. One question I have is what happens in a good pollinator year? If more native bees are present, will they be attracted to these traps or not? Surely, brown sugar would not be used as bait for a bee survey if it didn’t attract bees, right?

Based on my experience this year, I’m definitely going to try it next season. I’m thinking I would not erect the traps early in the season when wild bees are plentiful and wasps are few. Instead, I would wait until wasp populations start increasing and wild bee populations begin decreasing, a time that coincides roughly with summer dearth. The problem with that model is it gives the wasp queens a chance to establish a nest. Alternatively, I could just use the jug-style traps and skip the blue vane traps, which are designed to attract bees.

The trap details

In case any of you are interested in experimenting, the jug traps are made by cutting a square or circular opening in a one-gallon plastic jug (see photo below). The hole is about three inches on a side (or three inches in diameter for the circles) and is roughly opposite the handle of the jug. You put about six cups of brown sugar syrup in the jug and hang it from a tree about 4-to-8 feet off the ground. I tossed a rope over a limb and use it to raise and lower the jug.

Brown sugar syrup is made by dissolving 1 pound of dark brown sugar in a gallon of water (or one ounce sugar to one cup water). Why dark brown? I have no idea, but the directions I received have that particular phrase in bold, so I assume it’s somehow important.

Yeast, if you want it

If you want to use yeast, just add a teaspoon of active dry yeast at the time you load the trap. The yeast makes the traps smell raunchy after a few days, and I didn’t see any difference in the catch rate between yeasted and unyeasted syrup. Personally, I hated emptying the yeast traps, and tried to hold my breath. But I suppose it wouldn’t be so bad if I wasn’t collecting, washing, and bottling the sordid-smelling little bodies. Eew.

The location you choose for the traps should be open and sunny, at least part of the day. Try to find the kind of place where bees and wasps like to forage and hunt.

So that’s all I know. I thought it was interesting enough to pass on, especially since so many beekeepers have wasp woes in the fall. Please let me know if you try it.

Rusty
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