Conquer yellowjacket nests carefully


April 14, 2021

Ed Van Istendal, Territory Manager, Ensystex

Ed Van Istendal, Territory Manager, Ensystex

Anyone who has encountered a yellowjacket has immediately recognized its speed, aggression, quick defensive reactions, and also likely received a painful sting. From a single, fertilized, overwintered queen, yellowjackets can, from spring through early fall, create a nest of thousands for her daughters — and a few sons, for breeding purposes — that will start to expand exponentially, particularly by mid-summer.

Yellowjacket nests occur in a variety of places: attics, wall voids, behind exterior veneers of brick or stone, sheds, tree trunks, branches or stumps, unused vehicles, bushes, shrubs and even in the ground. This is a versatile pest that adapts well to a variety of sheltered or exposed areas. It is not unusual for a homeowner to be doing yard work and suddenly get stung by a yellowjacket. Perhaps he merely walked through their flight path, or was trimming a hedge where a nest is developing. Personal experience includes mowing over a subterranean nest — with a painful ending for both species!

Any exposed stinging insect nest that appears on a structure must be appreciated for what it is. If it presents on or near siding or painted surfaces, beware that some aerosol solvent mixes can strip away the oxidized layer of the colored surface, leaving a darker “stain” behind (which is actually the original color).

I recommend using a compressed-air sprayer with a registered residual material to douse the nest and its inhabitants. If not accessible because of height, a power sprayer can help with that reach. Remember that Sir Isaac Newton proved the laws of gravity long ago, and what you spray up must come down. It may be appropriate to tarp the drip area before you start.

If the nest appears to go into the structure, observe carefully. This is a great opportunity to use a light dust that travels well in voids. A lot of dust is not as important as a lot of air to move the dust fully into the void.

Free-standing, above-ground yellowjacket nests have a distinctive “paper” coating, like a large ball, that protects them from environmental extremes. Frankly, they are works of art, consisting of thousands of mouthfuls of the wood pulp and water slurry the workers make and bring back to the nest for building purposes. The nests, and the tiers of brood cells within, are all made of this paper, and it easily succumbs to the pressurized, registered mix coming from your power sprayer. These exposed nests are often confused with those of bald-faced hornets, but the same control technique works on them both.

Finally, we come to the subterranean yellowjacket nest. One great way to “coat” the nest with a control material is to put some of your finished liquid of choice in a dedicated container, then pour from it steadily into the hole — working within the label guidelines, of course. It may sound like overkill, but this prevents the interior shape of the hole and the nest structure from impeding the application process.

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