The Panic of SummerIn our mythologies of fright, it’s always the giants that come for us. Godzilla stomps Japan, Jurassic dinos shred the Park, aliens invade in mother ships. All scary stuff, or so we imagine. And yet if you want to witness a real-life display of sheer mindless terror, set up your camcorder at an outdoor picnic table laden with hot dogs, ketchup, relish, potato salad, and soft drinks, and wait for the fun to start. Within minutes, the inevitable cadre of yellow jackets will hone in on the same foods we enjoy so much, and suddenly all hell will break loose as the planet’s most dangerous predator swats and thrashes and runs screaming for cover from a few creatures no larger than the average human pinkie toe. It would be ironic if it were not so justifiable.
Getting stung by any member of the wasp family Vespidae is not an insignificant experience. Unlike honey bees, yellow jackets and their cousins the white-faced hornets can sting many times each, and while honey bee venom often causes a more severe individual reaction, multiple stings are life-threatening to anyone allergic to the toxin and ferociously painful in general. Like all wasps, yellow jackets and white-faced hornets will not hesitate to sting if annoyed and will defend their nests vigorously; at its peak a colony can contain thousands of workers ready to boil over at any provocation. And climate change may be working in Vespidae favor. A huge colony discovered in 1991 in Charleston, South Carolina, contained an estimated 250,000 adult yellow jackets. Apparently the preceding winter hadn’t been cold enough to kill off the hive as is the norm and the colony kept on producing workers. Just another aspect of global climate change to contemplate darkly.
Obviously, yellow jackets and white-faced hornets must be removed from dwellings and surrounding areas, and certain measures taken to avoid attracting their interest, such as not wearing perfume or scented lotions and shampoos outdoors and putting tight covers on garbage cans and picnic food, especially soft drinks. It’s also a good idea to keep an eye out for evidence of above or below-ground nests while doing yard chores. Bumping into a fully-loaded football-shaped hornet nest growing underneath the deck or chopping open an underground yellow jacket hive while attempting to harvest the potatoes can definitely sour one’s sympathies toward the natural world.
Yet the yellow jacket and white-faced hornet are in fact beneficial insects and important pollinators, and should not be exterminated willy-nilly even if that were possible, as was demonstrated in New Zealand a decade ago when that country’s agriculture department levied a bounty on German yellow jacket queens collected in the spring. The resulting mass destruction of overwintering queens had virtually no effect on yellow jacket populations the following summer. Entomologists later estimated that even if 99.9% of the queens had been eliminated, the same number of annual colonies would still remain.
A Vespidae queen overwinters in protected places such as leaf litter and hollow logs, emerging in early spring to start a small nest and lay her eggs. After the eggs hatch, the queen feeds the young larvae for about twenty days, until the first infertile female workers emerge. These workers immediately begin the tasks of expanding the nest, foraging for food, caring for the queen, and defending the colony, which at this point grows rapidly. When numbers are at peak size, reproductive cells are built and new queens and males produced. These adults are fed and protected until they leave the colony to mate. The males then die and the fertilized queens seek out new places to live out the winter.
Yellow jackets often build subterranean nests in rotten stumps, under firewood piles, raised garden beds mulched with leaf litter, in the sides of terraced walls, gullies or ditches, or under roof shingles. Nests in wall voids can threaten people inside the home if yellow jackets enter rooms through electrical outlets or molding gaps. Even underground, the nests are built of a papery wood pulp and completely enclosed except for the entrance hole and an entry port positioned beneath the tiers of combs.
The white-faced hornet, which resembles a large yellow jacket with a white face and white markings on the tip of its abdomen, is sometimes referred to as the “aerial yellowjacket.” This is the Vespidae that builds the distinctive elongated nest in trees, shrubs, or the underside of overhanging house structures. These nests can reach a prodigious size in a season, often escaping notice high up in tree branches until they contain hundreds of workers. White-faced hornets are as aggressive as yellow jackets in defending their nests but they cause little structural damage and are also beneficial insects in their own right. Unless they pose a direct risk, they should be left alone.
Yellow jackets and white-faced hornets are voracious predators of other insects, including caterpillars, horseflies, and the striped cucumber beetle, a serious pest of cultivated plants. During summer months, wasps can be observed hunting flies down on the wing; in fact the white-faced hornet is sometimes called the “insect hawk” for its habit of pouncing on its prey. In return, both serve as food sources; birds feed on adult wasps and in the fall, bears and skunks will dig into the ground and eat immature yellow jacket larvae. In their quest for food, yellow jackets will also scavenge rotting animal carcasses and fallen fruit as well as the disruptive picnic table setting.
Unfortunately, yellow jackets rob honey bee hives and are a serious stress factor for weakened bee colonies; though in nature’s way of balancing things out, white-faced hornets prey on yellow jackets, sometimes with a surprising demonstration of strategy. According to an anecdote published on a web site devoted to their preservation, white-faced hornets were observed hiding inside the exposed rib cage of a dead snake until yellow jackets landed to tear off bits of flesh –whereupon the hornets would grab their fellow wasps, kill them, and fly off with their prize grasped firmly in hornet jaws.
These are the habits of the predatory type of wasp, which includes the social Vespidae as well as solitary wasps such as the mud dauber. There are also parasitic wasps, usually so minute in size that we rarely notice them, though they are important ecological benefactors. Typically, they lay their eggs in or on the bodies of other insects and the emerging wasp larvae feed on the host body. One type of parasitic wasp consumes aphids as an adult and seeks out the tomato hornworm in which to lay its eggs. All of these wasp varieties working in and around gardens and cropland can remove a significant number of destructive agricultural pests.
Moreover, when examined closely, the relationship between plants, plant pests, and the intervening predacious wasp species reveals rather more about nature than perhaps it is entirely comfortable to know, as explained by Carl Zimmer in his gleefully macabre book, Parasite Rex: Inside the Bizarre World of Nature’s Most Dangerous Creatures:
When a plant is attacked by a parasite, it . . . fights by sending out
cries for help. When a caterpillar bites a leaf, the plant can sense it –a
feeling not carried by nerves but felt nevertheless. And in response, the
plant makes a particular kind of molecule that wafts into the air. The
odor is like perfume for parasitic wasps; as they fly around searching
for a host they are powerfully lured by the plant’s smell. They follow
it to the wounded leaf and find the caterpillar there, and they inject it
These conversations between plants and wasps are not only
timely but precise. Somehow the plant can sense exactly which species
of caterpillar is dining on it and spray the appropriate molecule into the
air. A parasitic wasp will respond only if the plant lets it know that its
[preferred] species of host sits on a leaf. [p. 181]
Better, one might conclude overall, not to venture outdoors ever again. Yet with care, careful management, and a modicum of appreciation, even the fearsome wasp family can be lived with, at least from afar.
Bald-faced hornets are best known for their large football-shaped paper nest, which they build in the spring for raising their young. These nests can sometimes reach 3 feet tall. Bald-faced hornets are extremely protective of their nests and will sting repeatedly if disturbed. The main area of the body that bald faced hornets attack on humans is the facial area.
There are six species of yellow jackets native to New York State. Yellow Jackets are shiny yellow and black wasps. Fertilized queens start nests in the spring in ground depressions or cavities or sometimes in hollow logs on the ground. A European species of yellow jacket was introduced into the northeastern United States about forty years ago. Unlike the native New York species, it prefers to build nests inside the walls of homes.
Ohio State University Extension Fact Sheet, “Yellowjacket” William F. Lyon ohioline.osu.edu.hyg-fact/2000/2075
Ohio State University Fact Sheet, “Paper Wasps and Hornets,” William F. Lyon and Gerald S. Wegner, ohioline.osu.edu.hyg-fact/2000/2077
Master Beekeeper “The Bee-Files,” Dyce Laboratory for Honey Bee studies, Dept of Entomology, Cornell University, www.masterbeekeeper.org/stinging/sting
Clemson Extension Service Home & Garden Information Center, “Yellow Jackets,” Wm Michael Hood, hgic.Clemson.edu/factsheets/HGIC2510
Department of Entomology, North Caroline Cooperative Extension, “Controlling Bald-Faced Hornets and Yellow Jackets around Structures,” Stephen B. Bambara and Michael Waldvogel, www.ces.ncsu.edu
Parasite Rex: Inside the Bizarre World of Nature’s Most Dangerous Creatures, Carl Zimmer, 2001, Touchstone/Simon & Schuster, New York.