One of the funniest things I have ever seen was when a friend of mine had a run-in with a yellow jacket (Vespula sp.) nest. I was far enough away to be safe, and the cause of his antics was invisible to me. While at the time it seemed funny, such situations can be very serious. The stings are painful, and if an individual is allergic, they can be deadly. Yellow jackets can sting multiple times so it doesn’t take very many of them to cause a big problem, and you don’t even get the satisfaction of knowing that they are going to die after stinging you.
Yellow jackets, for the most part, should be considered beneficial insects. They pollinate plants and are predators of undesirable insects, such as caterpillars that eat our favorite vegetables. Problems only occur when we have close contact with them. As my friend learned, they can be very aggressive when defending their colony.
Yellow jackets are at the peak of their annual life cycle in late summer and early fall. Since springtime, the queen has been laying eggs and growing the colony to its present size of several hundred to a few thousand female workers.
Soon, the colony will produce males and reproductive queens for a fall mating flight. The current queen and her workers will die out shortly after the first cool days of fall. There have been a few documented “super colonies,” which have survived the winter months and grown to extremely large sizes, but this phenomenon is rare. After the mating flight, the males will die. The newly mated females will land and find a suitable place to spend the winter months.
In the spring, a new queen will excavate into the ground, build a small paper nest and lay some eggs, which she rears to adult female workers. The workers then begin to take over rearing the young, collecting food, enlarging the nest and protecting the colony.
Nests usually occur in the ground, but yellow jackets will make a paper nest in tree and shrub branches or the hollow of a tree. They also are known to make nests in wall voids or attics. These nests can be particularly problematic because access to wall voids can be limited.
Because colony populations peak in the fall, people tend to have more encounters with yellow jackets. The most frequent story involves running a colony over with a lawn mower. So, let’s talk a little bit about control.
First Treatment Option:
If you can, avoid yellow jackets, don’t treat them. Treating yellow jacket colonies can be very hazardous work. It has already been said that they are largely beneficial anyway. If you are not willing to risk getting stung several times, consider hiring a pest or wildlife control operator to do the job for you.
Sanitation is an effective line of defense. Tight lids on garbage cans, keeping soda drinks covered and removing food sources can really reduce human/yellow jacket encounters. Frequent cleaning of dumpsters and garbage cans can reduce a number of insect pest problems, including yellow jackets.
Yellow jackets are very susceptible to most insecticides, however, it is often difficult to get the insecticide to the yellow jackets and eliminate a colony. For this reason, it is important to find the colony. You may need to spend some time watching your wasps to figure this out.
It is recommended that a colony be treated in the late evening or at night. This is not because they cannot see you or won’t sting at night, which is commonly believed. Be assured they can and will sting at night. Be wary of using a flashlight because this will attract their attention in low light conditions. The real reason for treating at night is because all individuals are in the colony and will be exposed to the treatment.
A number of aerosols are labeled specifically for bees and wasps. These usually have the ability to spray 10 to 15 feet, allowing you to treat from a safer distance. Most also have some sort of quick knockdown chemical, such as ether, which will almost instantly immobilize active workers. These have very little residual effect, and re-treatment may be necessary. They may also be a little less effective at delivering chemicals to the whole colony.
Insecticides formulated as dusts or soluble powders are particularly effective when placed in and around the colony entrance, but they do lack the quick knockdown of the aerosols. While very effective, this method carries with it the potential for attack as you get close to the nest. I use dusts and powders for colonies in wall voids and in the ground, and I recommend using expanding foam or caulk in wall voids to block the exit hole after applying the dust.
As with most IPM solutions, a combination of these tools might be the most effective. I’ve used aerosols to give quick knockdown, followed by dust formulations, to more effectively treat the entire colony. As with any insecticide treatment, use only products that are labeled for the target pest. Follow all label directions for the best and safest results.
A number of traps are available commercially. These are not designed to eliminate colonies, but can reduce the number of workers foraging in an area. They can also attract the wasps away from human activities. They require regular maintenance, but might be a great choice for environmentally sensitive situations.
For most people, yellow jacket stings initially are very painful, but a short-lived annoyance. A number of first aid products are available. Most of these products contain some sort of alcohol that cools the injury as it evaporates and relieves the pain. Home remedies should be avoided.
A smaller group of people can experience allergic reactions to the yellow jacket venom. Some reactions can be severe enough to cause death. The best first aid for allergic reactions is to get the individual to a doctor for medical attention as quickly as possible. If there is any doubt or question about treatment, consult a physician immediately.
As with any type of pest control, “what you know” is your most important weapon. What you are selling when it comes to pest control is not a particular chemical. You are selling your knowledge of how to use the all of the tools in the box whether it is a chemical control or cultural practice change. Choosing the right tool or combination of tools will allow you to successfully reduce the negative impact of yellow jackets on you, your workforce and your clients.