Ants and Yellow Jackets

Paravespula pensylvanica

Two of the most predominant summer and fall pest species we at Ecosystem Pest Solutions see on a daily basis are ants and yellow jackets. Both are social insects, which can make elimination from living spaces sometimes difficult. The former is mostly an irritant, but the latter can cause anxiety and often creates health concerns, especially if persons are allergic to the venom. These emotional responses can be eliminated or at least minimized by following a few basic steps and suggestions.

As homeowners, many of us consider ants a nuisance. The reality is most ants are generally harmless and are actually beneficial. For example, many ant species help our urban gardens by pollinating, dispersing seeds, breaking down organic matter, and aerating the soil. However, when ants invade our living spaces they become problematic.

Without a second thought many people grab an over the counter pesticide or insecticide (yes, there is a difference) and spray. Due to lack of knowledge about how environmental conditions, cellular and molecular biology, behavior, toxicology, and genetics work together, most of the time the problem gets worse, or the level of ant activity returns to pre-treatment status after a short reprieve.

The reality is indoor insecticide spray treatments rarely work. On the other hand, proper selection of and use of baits in targeted areas can prove very successful. Combine this with human behavioral changes and we can realize long-term success. The most important change we can make is better sanitation, one example of Integrated Pest Management (IPM). This can be as simple as cleaning the floor, spring-cleaning under the oven, or picking up pet food at non-feeding times. But even the cleanest of conditions still get inside ant activity from time to time. When this occurs it is best to contact an IPM professional. Other IPM methods include cultural, mechanical, and biological controls.

At the exterior, a simple pin stream foundation treatment is usually all that is needed for some ant species. But, as homeowners, we need to realize that conducive conditions (e.g. food sources, organic matter) play a large role in not only ant behavior, but in arthropod behavior as a whole. These conditions need to be identified and eliminated if we want to keep unwanted pests out of our living spaces. One of the best preventative controls is to remove the attractant. For example, thin out and keep vegetation off of structures, keep gutters clear of organic matter, rake and remove leaf debris from the foundation and adjacent areas, and keep watering to a minimum (i.e. don’t saturate foundation areas), as this may cause indoor movement.

Some ants, such as carpenter ants are known to cause damage to wood, but in a way, they can also be considered a detection device. Since they are attracted to wood that’s in a serious state of decay, any sign of carpenter ants could be telling you, at the very least, a 2×6 needs replacing, or worse, your main floor toilet is about to end up in your in-laws basement bedroom. Well, maybe that isn’t such a bad thing! Seriously though, when dealing with carpenter ants (three main species here in Oregon) it is best to have an inspection and consultation.

Yellow jackets (small genus of social wasps; Vespula) are carnivorous, primarily feeding on other insects during the spring and summer when their food sources are plentiful. Vespula have a foraging range of up to 2 miles, so their nest may not be near your home.However, these individuals are usually not a problem, and are actually providing us a service.

Yellow jackets are beneficial to the ecosystem. During the summer months, yellow jackets pollinate urban gardens and commercially grown fruits and vegetables as they go about their foraging activities, feeding on insects, such as caterpillars, aphids, and other crop damaging insects.

In addition, adult yellow jacket workers will feed on foods rich in carbohydrates and sugars, such as nectar and fruits when high-energy food sources are needed. This can lead to conflicts with human activity during the fall season. As Vespula summer food sources dwindle, they are attracted to and will scavenge for foods we consume, such as sugary beverages, meats, fruit, vegetables, and other BBQ picnic type foods. This is when you need to become more vigilant and be able to recognize local nest activity and behavior.

Yellow jackets fly in and out of their nest in a straight line. They rarely forage near the nest, and never hover, but may get backed up waiting to enter a crowded hole. When yellow jackets are on a mission (flying fast and in a straight line) they use the same flight path coming from or going to a nest. This is when you need to pay attention and identify (at a safe distance) where they are headed.

If you see insects performing fly-bys in a quick manner, continue looking in the same spot. If you see more, then you’ve most likely found the yellow jacket nest. Follow them until you can see where they’re entering and exiting. If you feel up to it, treat the nest yourself (dusts are usually the most effective), but approach carefully and only at night (an hour or later after sunset). This is when most of the workers are back in the nest.

During the day up to 80% of the nest is foraging.

Keep in mind, and a warning, yellow jackets are extremely aggressive from August into the autumn season, as they know they have a limited amount of time to forage. Food sources will increasingly becoming scarce, and they will defend the nest at all costs. Unless you have no regard for your safety, it is always advisable to call an IPM professional.

A bit of IPM advice. In the fall, as large numbers of Vespula create a nuisance around homes we need to be aware of our surroundings. As with ants, sanitation is the key. Make sure garbage container lids are completely closed. If you have more garbage than can fit in your curbside garbage container, consider purchasing a second container to temporarily store the extra garbage bag until garbage day.