Yellow jackets are eusocial predatory wasps. An overwintered yellow jacket queen begins a new colony in the spring by [...]]]> Late summer is the season when yellow jackets can be a problem for beekeepers. This is the same season that honey-robbing honey bees appear, and the miscreants can work together to produce a synergistic mess.

Yellow jackets are eusocial predatory wasps. An overwintered yellow jacket queen begins a new colony in the spring by laying a few eggs in a small nest, usually underground. Her progeny enlarges the nest, providing the queen more room to lay eggs. The daughter wasps care for the young, clean the nest, hunt, feed the young, and defend the colony. Both the nest and the colony continue to increase in size during the spring and summer months.

But just when the wasp colony is at its largest, the summer food supply begins to ebb. Less rainfall and higher temperatures mean foliage starts to dry and the insects that fed on the foliage are gone. You first notice the yellow jackets when they want to share your hamburger or sip your beer. They’ll go for soda pop, roast pig, or even corn-on-the-cob. These insects, previously in the background, suddenly come out of the woodwork. They are everywhere and they are mean.

Then, as the shorter and cooler days of autumn approach, even the alternative food sources dry up. But, although the picnic basket has disappeared, there is still fresh meat to be had . . . honey bees.

A well-populated colony of honey bees can successfully defend itself against a yellow jacket attack, but a small or weak colony can easily be overpowered by these aggressive and powerful wasps. Once in the door they will kill the bees. They will eat larvae, eggs, pupae, honey—whatever they can find. And they won’t give up until the hive is empty.

Several years ago a friend called to say that she saw some yellow jackets around one of my hives. I went over and watched in morbid fascination as three out of every four insects that went in or out of the hive was a yellow jacket. By the time I opened it, nothing was left. Even the comb was torn apart.

If a hive is weak, especially during a nectar dearth, other honey bees will often rob it of its honey stores. The fighting that ensues results in dead bees and open cells of honey—both of which can be detected by scavenging yellow jackets. If robbing gets well underway, yellow jackets are sure to follow.

So how do you prevent the carnage? In my experience, the best way to prevent an attack is to prevent robbing. As soon as nectar becomes scarce, close down the entrance to a size the colony can defend. A large and boisterous colony doesn’t need any restriction, but a small or weak colony may need its entrance reduced to one bee length. Make sure there are no alternate entrances where robbers or wasps can enter.

Also helpful are the plastic traps that contain a pheromone lure for yellow jackets. Hung in a tree or other structure, they attract the yellow jackets through a one-way entrance. Once inside, the wasps can’t find their way out. If you use these, hang them on the perimeter of the apiary but not too near the hives. The idea is to attract the wasps away from the hive, not toward it.

My other favorite yellow jacket control is to sweep them up in a butterfly net in the early spring. The very first ones you see may be queens. If you can get these, you can save yourself a lot of trouble later.

Rusty

Yellow jacket eating a honey bee

Pollen is usually in good supply before [...]]]> During these first warm and sunny days of spring, the bees literally climb over each other to get in and out of their tiny entrance. You’ve got the urge to remove the entire entrance reducer so they have plenty of room to move about. But be careful.

Pollen is usually in good supply before nectar and, until the nectar starts flowing, your bees are collecting mostly pollen—and craving a source of carbohydrates. If the entrance reducers are removed too soon, stronger colonies may take the opportunity to rob the weaker colonies of any honey they have left. If you see a great crowd of airborne bees in front of a weak hive, this may be what is happening.

So until nectar is plentiful, keep the entrance reducers on the weaker hives, and fully open only those you know to be strong and populous. After nectar becomes more available, the weaker colonies will expand and soon be able to defend their hives. At that point, you can enlarge their entrances or remove the reducers altogether.

Rusty

But late last [...]]]> Up until this week I hadn’t seen many yellow jackets. Since 2009 seemed to be “the year of the yellow jacket,” I was expecting to see fewer this year. Nevertheless I had yellow jacket pheromone lures hanging nearby and my hive entrances had been reduced for a month. Everything seemed fine.

But late last week I decided to stack my two smallest colonies for the winter. They both were started from nucs during the summer, and they both covered somewhat less than ten frames. I decided to stack them, separated by a double-screen board, with one entrance in back and one in front—the same orientation they had all summer. In a few weeks I would stack both on top of a strong colony with another double-screen board. If all went well, the large colony would help keep the two smaller ones warm.

Somehow, though, everything went wrong. When I moved the two colonies, I must have broken some honeycomb. A small amount of honey started dripping through the varroa screen. The hive stand is about two feet high, so this honey fell from the screen and oozed into the ground in the empty space under the hive. Of course I didn’t notice it at the time. I stacked the hives, opened the proper entrances and walked away.

About three hours later I noticed a cloud engulfing the stacked colonies. Bees were everywhere. They were zipping through the trees, careening past the kitchen window, and milling above the driveway. There were more bees than could possibly come from those two colonies.

On inspection, I realized what had happened. The drips of honey had created a robbing frenzy. Since we are in a nectar dearth, bees from everywhere descended on these two small colonies. Fighting was rampant. Bees on the lid, on the landing boards, and on the ground were engaged in mortal combat. Pairs of bees spun like tops from the combined action of their wings. Dead bees were everywhere. I immediately shut down the entrances to almost nothing.

The real winners in this mess were the yellow jackets. Smelling death, these wasps—or “meat bees” as they are sometimes called—arrived in waves. They feasted on dead honey bees, drips of honey, and lost pollen loads while the honey bees continued to kill each other. Also collecting the spoils of war were bald-faced hornets and a legion of ants. The wasps made repeated attempts to enter the hives while the honey bees were busy fighting each other. I watched nervously, but the reduced entrances were being defended and I didn’t see any wasps make it inside.

The frenzy lasted for two days. The fighting finally stopped. The yellow jackets are still scavenging, but there are fewer. The dead bodies have been carted off by one creature or another. I have no idea how bad the losses to the two young colonies were, but I’m certainly not going to open them now to find out.

The real lesson here is to be careful during a nectar dearth. I should have stacked those colonies earlier—before the dearth—or later, when it’s too cold to fly. Also, I should not have assumed there were no wasps just because I hadn’t seen any. They were just lurking in the shadows, waiting for someone like me to provide them a feast.

Rusty

Yellow jackets snack on dead honey bees. Photo by the author.

The robbing bees may come from within an apiary or from [...]]]> Robbing is a term used by beekeepers to describe bees that raid another hive and take all of the honey back to their own hive. Robbing is particularly prevalent during nectar dearths that occur in the warm months of summer or early fall.

The robbing bees may come from within an apiary or from neighboring areas. At first glance the cloud of robbers may look like a small swarm or a group orientation flight but, on closer inspection, the beekeeper will see that the robbing bees are all older foragers. They are in a frenzy, and there may be fighting at the entrance. Although fighting is a sure sign of robbing, if the bees in the invaded hive have already surrendered or the guards have been killed, fighting may be absent.

Robbing is triggered by the smell of honey. It often starts just after a beekeeper has opened a hive for inspection, for feeding, or to remove honey supers. In less than an hour after opening, a hive may be engulfed in a black cloud of invaders.

Robbers are not at all gentle or neat. They rip cells open, leaving waxy shards on the bottom board and jagged, rough edges on the comb. They may kill many bees, including the queen, to get what they want. Although they leave at nightfall, they will be back bright and early the next morning. Robbing is always a case of the strong preying on the weak.

It is difficult to stop robbing once it starts, but here are some things you can try:

• Completely cover the hive with a wet sheet to keep the invaders from getting in.

• Close up the hive completely for several days until the robbers give up. Be sure to provide feed, pollen, water, and ventilation for the confined colony.

• If you don’t have screens, reduce entrances and fill remaining openings with grass.

It is much more effective to anticipate robbing and take preventive measures than to try to stop it once it starts. Here are some strategies that may work—at least some of the time.

• Reduce entrances at the first sign of a nectar dearth. Bees can successfully defend their hive if they have a large enough population and a small enough entrance.

• Many beekeepers have observed that Italian bees rob more often than other sub-species. If you keep Italians, you should be more vigilant.

• It appears that queenless hives are more vulnerable to robbing than queenright hives. Make sure all your hives are queenright as robbing season approaches.

• Entrance feeders seem to promote robbing more than other feeders, probably because the food source is so near the hive opening. Use some other type of feeder during nectar dearths.

• Small or weak hives are particularly vulnerable. Consider combining such hives before a nectar dearth.

• Commercial robbing screens are highly effective devices that allow the resident bees to get in and out while discouraging the robbers. These can be especially valuable for use on weaker hives that you do not want to combine.

Rusty