Photo: Johnny N. Dell, Bugwood
It’s been a good year for baldfaced hornets. Many people have contacted me to report their grey papery nests in trees or hanging from the eaves of their homes.
So, are they good guys or bad guys? Do they need to be controlled? It’s a matter of making an informed choice. So here are the facts.
First, baldfaced hornets aren’t hornets at all. They’re black and white yellowjackets that nest in trees, shrubs, and on buildings. Since they kill many harmful pests, they are considered beneficial.
It’s only when their nests are nearby that they pose a potential threat from stinging. Left alone, they tend to be benign. They usually only sting to defend their nests. I’ve had several walk up and down my arm peaceably.
The white marks on their head earn them their “baldfaced” moniker. Workers measure about three-quarters of an inch long and queens are slightly larger.
In the spring, overwintering queens emerge from tree bark, stumps, logs, rock piles, and other protected spots. Each queen builds a small nest with a few brood cells, lays eggs, and gathers insects to feed the growing workers.
When those workers become adults, they take over the housekeeping duties, building and taking care of the nest, foraging for food, and tending to the growing family from eggs laid by the queen.
Baldfaced hornets’ football-shaped nest is an engineering marvel. To that first handful of paper cells, workers add layer upon layer of hexagonal combs similar to those of the honey bee.
To make each cell, they gather wood and plant fibers and chew them into a papery pulp they use as a building material.
Halfway through construction, the nest looks like an upside-down funnel with a long tube. Workers build around the tube to create a nest that may be home to over 300 family members by summer’s end.
The finished nest can be over a foot wide and two feet long, tucked into a low shrub, or 60 feet up a tree. I’ve seen them dangling from sheds, saplings and even plastered on a Palladian window.
From July to September, new queens and males are made which leave the nest and mate. New queens look for a cozy spot to spend the winter. The original queen and workers die and the nest isn’t reused.
Again, baldfaced hornets are beneficial, so tolerate them if you can. They gather a tremendous amount of harmful insects to feed their young and themselves. In late summer, they also pollinate flowers in their search for nectar.
However, if their nest is near where you’re active, control is an option. If you are allergic to bee stings or nervous about doing this on your own, leave the job to a pest control professional.
If you tackle this on your own, treat the nest at night or early morning when most of the hornets are inside but there is still some natural light. Direct a wasp and hornet spray at the entrance, carefully following the directions.
But again, I encourage peaceful coexistence. Baldfaced hornets are amazing engineers and fascinating insects that help to manage garden pests, pollinate plants, and maintain a healthy ecosystem.
By Annette Cormany, Principal Agent Associate and Master Gardener Coordinator, Washington County, University of Maryland Extension. This article was previously published by Herald-Mail Media. Read more by Annette.