Late summer is the season when yellowjackets 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.
Yellowjackets are eusocial predatory wasps. An overwintered yellowjacket 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 yellowjackets 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 yellowjacket 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 yellowjackets 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 yellowjacket. 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 yellowjackets. If robbing gets well underway, yellowjackets 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 yellowjackets. Hung in a tree or other structure, they attract the yellowjackets 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 yellowjacket 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.