Yellowjackets don’t always nest underground

Most homeowners think of Yellowjackets as ground-nesting wasps, but in Northern Illinois they frequently establish nests inside exterior walls, chimneys, soffits, attics, voids around fireplaces, etc. These are locations that provide protection from weather and predators while allowing workers to enter and exit through tiny exterior openings.

How do I know if I have a Yellowjacket nest in my wall?

On the outside, you’ll notice a steady stream of small wasps moving back and forth from some sort of opening in the home. Often times this is in the soffits, or in other home trims where materials meet. They can establish in areas of the home high off the ground, so are often unnoticed until the colony is in the thousands.

On the inside, you may notice the steady hum or buzzing of worker Yellowjackets fanning the hive, or even a scratching or very light tapping sound on a section of wall of your home. When they build nests in homes, they’ll frequently end up building it along a section of drywall in a wall or ceiling void, so as the nest expands they will chew the drywall to make space.

This is particularly dangerous since they will eventually reach the point where they will eat through the drywall entirely and enter the home. Once they see the light from the inside of the home, dozens or even hundreds of them will begin to enter the affected room. In a way, that part of your home has become part of the nest, so they are liable to protect it as such.

If Yellowjackets have made a nest inside a wall void, professional pest control is strongly recommended as incorrect handling can potentially release hundreds or even thousands of angry Yellowjackets into the home.

Locating hidden nests

Thermal imaging

In many cases, active Yellowjacket nests generate enough heat to be visible with a thermal imaging camera. The concentration of insects and continuous activity will create a warm spot on walls or ceilings that helps technicians pinpoint the nest location.

The images above show how a Yellowjacket nest that is nearly invisible to the naked eye can appear as a bright thermal signature on an infrared camera. The images allowed the technician to treat directly into the core of the nest, giving much quicker and more reliable results than treating from the outside entry point.

Sound

A mature nest will have thousands of workers with various roles. Many will fan the nest to dissipate heat, creating an identifiable buzzing noise you may hear through your wall. Many others will be further expanding the nest, which may involve digging through the drywall. As they bite into the material, it creates a loud clicking/tapping noise. The following audio is best listened to with headphones on, but demonstrates the noise these wasps emit as they dig through the drywall

FAQs

Can I find a Yellowjacket nest without a thermal camera?

Often times, yes. They will emit a buzzing sound and a tapping/scratching sound as they dig through the drywall, which is the first warning of an issue. As Yellowjackets build a nest against drywall, they’ll often leave greasy stains that discolor the interior side. You may also notice a soft spot where the drywall has become thinner. Be careful not to poke any holes in the wall, as sometimes it is just a thin paint layer remaining to the interior, and such a disturbance will be treated as an attack on the nest by them.

Why do Yellowjacket nests emit heat?

Mature Yellowjacket nests contain up to several thousand workers. The constant movement of insets, wing fanning, brood development, and overall activity generates heat which can sometimes be detected through drywall or ceiling materials. While not every nest produces a visible thermal signature, large established colonies frequently appear as localized warm spots.

Can Yellowjackets chew through drywall?

Yes. In cases where a growing nest is against a wall, they will often eventually chew through it. When this happens, large numbers of Yellowjackets may suddenly appear inside a room, often around windows, light fixtures, or ceiling areas

Will a Yellowjacket nest damage my house?

Most wall nests do not cause structural damage, but they can damage drywall, insulation, and other materials as the colony expands. The greater concern is the risk of Yellowjackets entering living spaces or stinging occupants if the nest is disturbed

Should I seal the hole where Yellowjackets are entering?

No. Sealing an active nest can trap workers inside the wall and forces them to search for alternative exits. This can result in Yellowjackets entering the home through light fixtures, vents, or other openings. The nest must be completely dead before entry points are permanently sealed

Will a Yellowjacket nest go away on its own?

In Northern Illinois, most Yellowjacket colonies die off after the first hard frosts of fall. However, waiting for winter may leave homeowners dealing with months of Yellowjacket activity, and active nests will continue growing until around October, when cold weather signals the Yellowjackets to abandon the nest

Will Yellowjackets return to the same nest next year?

No. Yellowjackets do not reuse old nests. However, if the original entry point remains open, a new queen may establish a colony in the same wall cavity during a future season

What time of year are wall nests most noticeable?

Most homeowners notice wall nests during August and September. By this point, the colony has reached its largest size, Yellowjacket activity is at its peak, and buzzing noises become much easier to hear