Yellowjackets

Family: Vespidae
Species: Paravespula (Vespula), Polistes spp.

Identification:

Most people can recognize a wasp when they see one. They are conspicuously colored to remind us of who they are. Yellowjackets, Paravespula, are the typical black and yellow banded wasp that most people are familiar with. Paper wasps, Polistes, have more of a red and yellow color with a little black. The larvae of both kinds of wasps are the typical, leg-less grub form. You will rarely encounter the larvae unless you open a live nest (something I don’t recommend). Yellowjackets will envelop their nests in a papery layer while paper wasps will leave the inside cells exposed.

Its not a coincidence that we use the same pattern, black and yellow, to warn or caution others of a potential danger (such as caution tape around a road hazard). These colors are universal. Insects, being the exploitive critters they are, will mimic these colors to fool potential predators. Almost every order of insects has representatives that do this. A common example is that of the aphid predator, the hover fly. This fly will even poke you with its abdomen to scare you into thinking that it’s stinging. Many clearwing moths also mimic yellowjackets, such as the raspberry crown borer. As general rule, wasps will be hairless, have two sets of wings, a constricted abdomen and an ovipositor in the shape of a stinger.

Life History:

Wasps are ‘eusocial’ animals. Like bees, ants and termites, wasps live together with overlapping generations, there is a large amount of parental care for the offspring, they have a caste social structure with sterile workers and divisions of labor, and have a complex system for communication. Eusociality is truly an amazing way of life. Colonies of individuals behave more like a single being and the individual workers are like organs, each performing a function to keep the colony alive.

The queen is the only survivor of winter. She will spend the winter in a protected shelter like a dead log, ground litter, or your attic. In my case last year, this was on the side of my bedroom wall. I thought it was pretty cool to have a yellowjacket hibernating in my room, until one day it was gone. I found it a few weeks later when I put on a t-shirt. Yellowjacket venom is a much more potent eye-opener to start your day than any cup of coffee I’ve ever had.

Once spring comes, she will find a nesting site and construct a small hive of a dozen or so cells. She diligently maintains this first brood, constantly hunting, feeding, building and providing for her daughters. Once this brood matures, the sterile daughters take over the hard work while the queen devotes all her time to reproduction. As the season progresses, the colony grows. Colony sizes peak around now, September and October. Late summer and early fall, is the time of year that wasps become a problem to most people. Yellowjackets, hornets and other wasps are voracious predators. This is the time of year that insect populations drop, yellowjacket populations are peaked and competition for food is high. Wasps can become very aggressive and persistent about getting what they’re after. Colonies can reach the size of 5,000 workers, depending on the species. By the end of the season, males are produced and mating occupies the time of future queens. After the cooler temperatures settle in, the hive dies and is abandoned. They will not reuse the hive as a future-nesting site. Pending on the species, sites are either protected underground, between walls, in rock piles, or exposed in trees, under housing eaves, and attic ceilings. There are subterranean types of nest builders and arboreal (tree-dwelling) nests. This is species specific.

Damage:

Have you ever had the unfortunate experience of disturbing a large yellowjacket nest? As you were sprinting, swatting and screaming yourself away, did you ever notice that you smell bananas? Many species of yellowjackets produce the smell of bananas to alarm other nearby wasps of a potential threat to the hive. This is part of their communication system; they use chemicals, pheromones, to send signals and information. Unlike bees, wasps can sting you as many times as they want. This adds to the severity of wasp attacks. You can receive a large amount of venom if at the wrong place, at the wrong time. Like bee stings, people can react very violently and undergo anaphylactic shock as an allergic reaction. In fact, it’s thought that wasps kill more people per year than any other animal. The most likely scenario is a disoriented, angry wasp flying into a speeding car’s window and a panicking driver losing control trying to swat the wasp.

It is important to point out that yellowjackets are extremely beneficial insects. They are voracious predators. We would have serious pest problems if it weren’t for yellowjackets. Workers are continually hunting other insects to bring back and feed to the next brood. Caterpillars and flies are commonly used as a food source for yellowjackets. I’ve seen wasps try to fly away with caterpillars three times their size. After a few unsuccessful attempts, the wasps will bite the caterpillar in two and come back later for the second half. In fact, yellowjackets are used as biological control agents in corn, cotton and tobacco crops. A few well-placed nests can clean acres of crops of any pests.