Yellowjackets: Where's the Meat?

Without a doubt you have suffered through a memorable experience with "Meat Bees" at some time or another. This may have been while hosting a barbecue in your back yard at a 4th of July celebration, perhaps while at a picnic at a local park, or possibly while camping in a mountain area. I too, have had my share of run-ins with "meat bees", more properly called Yellowjackets. I have been stung while gathering firewood while camping, stung while pushing some branches aside on a walk, and most recently stung while mowing a lawn, the mower passing over an underground nest of yellowjackets.

Yellowjackets are wasps, not bees, although that's small consolation when you are running for your life! So, why do we call them "meat bees"? Well, like most wasps, yellowjackets are predators. The larvae (the worm stage) are fed meat by the adults, which fly around looking for such sources. Yellowjackets are one of the "social" wasps, in that they live in a colony that was started early in the year by a single Queen. Her egg laying activity can result in that colony reaching to as many as 25,000 workers by the end of the year.

Social wasps, like honeybees and ants, have societies of workers who care for their babies (the eggs and larvae), who gather food, who work to build the paper nest and enlarge it as needed, and who protect the colony when they feel threatened - such as by my lawnmower rumbling over the opening to their colony.

Do yellowjackets "bite" or "sting"? Well, probably both, but their primary means of defense is with their stinger, a modification of their egg laying device at the end of their abdomen. When they poke this into your skin they pump in some venom, and that is what causes the immediate, searing pain, which actually could be very dangerous to a sensitive person or pet.

So, why do they hang around picnics and barbecues? Well, for two reasons. Remember, I mentioned earlier that the larvae eat meat. Now, in a natural setting there are not a lot of hot dogs or hamburgers growing on trees, but yellowjackets often obtain the same meat from dead animals they find laying on the ground. Have you ever noticed some of them hovering or crawling over a dead fish? Hunters complain of having their prizes eaten off of by yellowjackets, and one fisherman once bemoaned the fact that a likely world record bass he had caught had about 3 pounds of meat removed by yellowjackets, lowering it to below record status.

Yellowjackets and other wasps also feed heavily on insects - crickets, caterpillars, grubs, or other bugs slow enough not to scamper away. In this respect, obviously, they are beneficial, but when they perceive our barbecue foods to be tasty, we have a big problem.

Now, only the larvae eat meat. The adult yellowjackets - the ones we encounter - feed on sweet tasting liquids. In a natural environment the sweet liquids may be oozing plant saps or nectar from flowers or fruit, but they commonly may be "honeydew" - those sticky, messy, but wonderfully sweet drippings from aphids and scale insects that feed on our plants. Around the barbecue or picnic the sweet liquids are jelly sandwiches, fruit salads, and sodas (but not the "diet" kind - yellowjackets don't care for artificial sweeteners.

A yellowjacket colony consists of a single Queen and dozens or many thousands of workers, all of whom are females. Male wasps are produced late in the season to mate with new Queens, after which the males die, and the now fertilized Queens hibernate through the cold winter and start their own new colonies in the spring. The earlier they can get started, the bigger their colonies can build to. So, if we have a mild winter and early warm temperatures, we'll have yellowjacket problems building sooner and bigger.

Also, if we have a really mild winter, or if you live in a part of the country where winter temperatures normally stay well above freezing, the colony could survive right on through. One documented colony in northern California lasted 3 years, and had a 6 foot tall nest (!!!) with 113,000 yellowjackets in it, and this was in bushes in a neighborhood.

So, now we know something about yellowjackets and how they grow. Now, what do we do to get rid of the pesky things. Even though we must acknowledge that they are beneficial, in their role of eating other insects, they also easily are classified as "PESTS" because of their ability to sting. As a social wasp they communicate, and once you have angered a couple of them, they give off odors called pheromones which get the rest of them mad too - "Mad as a Hornet" is quite an appropriate term, and they will fly around aggressively until their pheromone-rush is calmed, stinging anyone or anything that wanders in. And, unlike honeybees, wasps can sting as many times as they please.

Controlling Yellowjackets

The first step in controlling any pest is to make certain that you really are dealing with what you think you are. In other words, identify it correctly. There are many kinds of beneficial flies that closely resemble wasps, and there are many kinds of "solitary" wasps, such as sand wasps, which also look exactly the same as yellowjackets, but pose a far, far lower hazard to you.

        

 

The problem kinds of yellowjackets are the ones we call "scavengers" - the kinds likely to ignore natural foods and instead go after our picnic foods. They may create their paper nests in either the ground or the air, hanging a nest from a branch of a tree or under the eaves of a house, or, very commonly, in walls or attics or crawlspaces of homes. This is when they become most dangerous to people, and many times they will chew right through the walls and get into the house.

Another, very common, location to find the peskiest of the yellowjackets is in the soil. The Queen may find a small hole in the ground where she initiates the colony, and from that small beginning the workers continually enlarge the hole to accommodate their ever-growing colony size. Even in the ground, however, a paper nest is constructed to house all the eggs, larvae, and pupae, and many thousands of workers can be present there as well.

Once you have ensured you are, definitely, dealing with yellowjackets, here are some options to consider:

  • Yard cleanup - eliminating piles of yard or lawn trimmings, piles of lumber, or other unnecessary debris on the ground will eliminate much of the shelter the yellowjacket Queen looks for in establishing the initial nest. Cleaning up fruit that has fallen on the ground will take away a food source and attractant and help keep yellowjackets from congregating in your yard. This is especially important in late summer and fall, when we have a double edged sword - not only are we more likely to have the accumulation of foods, from apple or pear trees, tomato plants, etc., but the yellowjacket colonies also have reached a peak in their population.
  • Sanitation - cleaning garbage cans, tabletops, and other surfaces where we have spilled food. This, too, attracts the yellowjackets, as well as nasty flies that we would really prefer not to share our table with. If you look around your yard and find a buildup of the shiny, sticky honeydew on the plants (from the aphids) you should consider washing it off with the garden hose. You can speed that process up with a hose-end sprayer attachment with some liquid detergent in it.
  • Watch What You Wear! - yellowjackets may be attracted to certain colors (yellow, orange, or purple seem to be favorites) or odors, such as perfume or cologne. Commercial insect repellents do not seem to do much to deter yellowjackets.
  • Trapping - various kinds of traps are available, designed to entice yellowjackets in, where they are trapped and cannot escape, dying within the trap. These can be laced with baits that may come with them, or with meats or sweets that you can buy yourself. Those that work well are fish baits - sardines, mackerel, salmon - or citrus flavor soda syrups. Traps should be placed away from those areas where people frequent, to draw the pests away from people rather than to them. Experience seems to indicate that, while you will no doubt catch a lot of yellowjackets, you should not expect to eliminate an entire colony simply by using traps.
  • Spraying or Dusting - this works well, and may be the method chosen by a Professional Pest Control company, should you contract with one to take care of the problem. However, these experts have protective clothing and application tools you may not, as the chemicals may excite the yellowjackets when their nests are sprayed or dusted.
    Generally spraying a yard area is of little value, and "directed spray" aerosol cans are designed more for the smaller, exposed nests of "Umbrella Wasps".
  • Baiting - this is an ideal method, as it provides food mixed with a toxic product, which the foraging workers collect and take back to the nest to feed to their larvae. In the process they kill not only all the larvae, but also themselves, as they are exposed while carrying the meat in their mouths.

    Only one pesticide is labeled for this, and it is not generally available to the retail market. However, it is used widely by the professional pest control industry which is trained in how to use it correctly and with little exposure to animals that are not intended for it. Contact a licensed pest control company if you would like more information on this.

Yellowjackets are certainly "beneficial" in their role as predators of other bugs, but there are times that their presence in our yards or homes cannot be tolerated.