Yellowjackets: A Look at Opportunistic Raiders of Honey Bee Hives
By Edward Ricciuti
The boom in backyard beekeeping in recent years has been great news for at least one group of fellow hymenopterans: yellowjackets. Honey bees are high on the menu of insects on which yellowjackets feed; besides killing and eating individual bees, yellowjackets also raid hives for larvae, pollen, and honey. More beekeepers means more bees to consume and hives to pillage.
To be sure, yellowjackets—a term used in North America for two genera of social wasps, Vespula and Dolichovespula—are not a leading (or even significant) cause of honey bee colony losses. But when yellowjackets do target honey bees, they hang around the entrance of a hive waiting to ambush and pick off individual bees as they come and go. They quickly dismember a bee after killing it, eating some parts and carrying a portion back to feed their own larvae in their own nest. Beyond that, says Mark Creighton, master beekeeper and apiary inspector for the State of Connecticut, healthy hives are seldom seriously threatened by yellowjackets.
A similar opinion is voiced by author of the highly regarded book The Sting of the Wild, Justin O. Schmidt, Ph.D., of the Southwestern Biological Institute in Tucson, Arizona: “In North America,” he says, “yellowjacket predation on honey bees is not a major problem in most cases.”
That’s because honey bee (Apis mellifera) hives have a formidable defense. Worker bees assigned as guards fight off intruders with stings, and they will also cluster in a ball around individual yellowjackets and “cook” them to death with body heat, which has been recorded at more than 120 degrees Fahrenheit. A dozen or so bees can do the trick on one yellowjacket.
If a hive weakens, on the other hand, all bets are off. Attacks by yellowjackets can go from a nuisance to a genuine problem and even lead to hive collapse, says Creighton. Yellowjackets easily sniff out chemicals that reveal weakness in a hive, upon which they trigger an all-out assault by chemically signaling for reinforcements. They then proceed in looting honey cells and killing bees, often including the queen.
Many forces can weaken a hive, including chemical pollution, pesticides, and poor management. The increasing numbers of novice beekeepers, says Creighton, increase the likelihood of management mistakes, improving opportunities for rapacious yellowjackets.
To avoid mistakes, says Creighton, novice beekeepers should take an introductory course and learn from a mentor. He explains that beekeeping in North America has become more demanding since the 1990s, due to the tiny brown Varroa mite, which has spread almost worldwide from Asia. Its scientific name, Varroa destructor, is frighteningly appropriate because it feeds on bees and spreads viral disease that kills hives—worldwide, it is generally regarded as the worst of all bee parasites.
“The Varroa mite changed everything,” says Creighton.
A hive has a full menu for a hungry yellowjacket: adult bees and larvae for protein plus honey and pollen for carbohydrates. Hives and the bees living in them are particularly important later in the season because other prey insects and nectar sources are dwindling. “In mid-to-late fall when food is scarce and some honey bee colonies are weak, yellowjacketes might invade and do some serious damage.” says Schmidt.
Even if experts downplay damage caused by yellowjackets, the predators take plenty of flak for wrecking hives. Beekeeping organizations and state agricultural agencies churn out a flood of information on how to fight off the yellowjacket hordes. Countermeasures range from simply narrowing the entrance to the hive to prevent easy access by predators to a host of eradication tactics.
This concern seems to be a tad of overkill. “Overall,” says Schmidt, “yellowjackets are beneficial insects, and their benefit outweighs their harm to bee colonies.” Indeed, yellowjackets prey on a variety of grasshoppers, aphids, flies, and caterpillar pests. They may be at times a beekeeper’s bane but overall can be a boon for agriculture.
Part of the reason why yellowjackets have taken such a bad rap in this country, says Schmidt, is because of confusion involving yellowjackets and hornets, much of which is caused by local and common names given these insects. Yellowjackets and hornets are both wasps in the family Vespidae. But they are by no means the same. “Yellowjacket” is a name given in North America to two groups of wasps, the genera Vespula and Dolichovespula. The latter in North America is represented by what most people call the “bald-faced” or “white-faced” hornet, although it really is not a hornet but rather a yellowjacket.
Hornets (genus Vespa), meanwhile, are not native to North America, although the European hornet (Vespa crabro) has been introduced there. In Europe and Asia, however, hornets are a serious problem to beekeepers. The notorious giant Asian giant hornet (Vespa mandarinia), a beast two-and-a-half inches long, is a true plague of honeybee hives. It is spreading and could be a nightmare for beekeepers if introduced here.
Speaking of introductions: One of the most abundant, widespread, and aggressive of the wasps that North Americans call yellowjackets is, in fact, not native to North America but rather introduced from the Old World. In North America, it’s called it the “German yellowjacket” (Vespula germanica). In Europe, however, it is just a “wasp.” There is a good reason for scientific names.
Ed Ricciuti is a journalist, author, and naturalist who has been writing for more than a half century. His latest book is called Bears in the Backyard: Big Animals, Sprawling Suburbs, and the New Urban Jungle (Countryman Press, June 2014). His assignments have taken him around the world. He specializes in nature, science, conservation issues, and law enforcement. A former curator at the New York Zoological Society, and now at the Wildlife Conservation Society, he may be the only man ever bitten by a coatimundi on Manhattan’s 57th Street.
I have seen the 2 fighting apparently over the nectar of banana flowers.
While I agree with some comments expressed in this article, I disagree with the underlying premise that somehow yellowjackets won’t predate a strong honey bee colony. Last fall we saw many of our strong production hives get slaughtered by yellowjackets. While I agree that there are often underlying causes in why a weakened hive is predated, we took some very, very heavy hits on hives that were otherwise strong. In some yards we had 100 per cent kill of our hives, despite reducing entrances. I posted a video on our facebook page that shows just how heavy the predation was in one of our yards. @honeybeezen
Yellow jacket populations vary greatly from one location compared to another.
In some years here in Oregon particularly if next to vineyards, the populations become unbearable.
Our honey yards in such locations typically have 32 – 48 hives.
The jackets have been so thick, that it looks like the ground is moving.
Regardless of all else, they do take a toll on the bees.
And once they begin to overtake a hive, they all start pounding that one hive until it is stripped clean.
With the warmer, longer seasons, this is becoming an increasing problem
Last summer my hive of Italian bees was decimated here in Northern California. Ended up following the yellow jackets back to their in ground hives and destroyed three of them. The day after destroying one yellow jacket nest I would see no reduction of the yellow jacket population circling around in front of the bee hive. At the urging of a neighbor of mine, I contacted Sacramento County Mosquito & Vector Control (Vector Control tries to eradicate any animal that can transmit disease–which yellow jackets can do after they forage on decomposing animals). They sent a team out and found 32 active yellow jacket nests within the American River Parkway behind my house and within a quarter of a mile of my backyard. I will be interested to see if they were able to put a dent into the population by destroying those nests….crazy.
Fall 2021 central NJ – the yellow jacket population was so great it destroyed my 2 very healthy hives in days. My guess is, as the hive population decreases naturally for winter, the
very sizable wasp population didn’t due to warm weather. But there was reduced food supply for the yellow jackets. It would continue until freezing weather and food supply kill them off. There was a greater overlap of strong numbers of starving yellow jackets and reduced honey bee populations at hives. Shear numbers prevailed. Two weeks later the yellow jackets are still picking the remnants of the hives. It can come down to a matter of numbers and 1 and 2 hive hobbyists are more vulnerable to total loss than large apiaries – again, a numbers game. Sounds crazy?, but I’ll be experimenting with netting enclosures for my hives as soon as foraging value ends for the honey bees and before yellow jackets focus turns to the hives next season. Could be a decent hobbyist approach – but unlikely any commercial value. I’ll get away with it because I take very little honey, will feed slightly and provide a water supply and a large enough enclosure for cleansing flights. Any other ideas out there for the hobbyist?