Photo © by Ruby Jung. All rights reserved.

Bald-Faced Hornet Nests

Hornets have an unearned reputation for viciousness. I've gotten up close and personal with dozens of nests and have only been stung when I actually disturbed the nest (not recommended). Bald-Faced Hornets are generally mild, inoffensive creatures and often are unnoticed until late summer or fall when their nests reach large sizes. Many homeowners are surprised to discover an abandoned nest in a tree after leaf fall. The nests themselves are made of paper from old wood chewed up in the wasps mandibles and then squeezed flat - sort of an insect paper mache - and require constant repair and maintenance.

Each nest begins with a single fertilized queen who emerges from hibernation in our area in late April. The queen builds a few paper cells with a tiny awning over it and lays a single fertilized egg in each cell. When this first generation hatches the queen feeds her larval daughters (nearly all wasps are female) with spiders she's caught and the larvae grow rapidly. After pupating for a week or so the youngsters emerge and begin constructing more cells and a more elaborate nest covering to enclose them. The queen then lays an egg in each new cell and her daughters help in the feeding and care of the young.

Photo © by Jim Jung. All rights reserved.

By August a typical nest will contain several hundred adult female worker wasps and one queen - their mother. It's at this time that the sterile worker wasps raise a brood of fertile queens and drones (male wasps). Whether this larval change is brought on by a special diet administered by the worker wasps as it is in honeybees or because of some special property of the eggs laid is unknown - at least to me. At any rate both fertile males and females are produced and as fall arrives they fly off in search of mates.

The stingless males die immediately after mating and the now fertilized females seek out a safe place to sleep the winter away. As cold weather approaches the old queen dies and her colony, now leaderless, disperses. Any surviving wasps in the nest are killed by the first cold snaps of winter though I've never encountered any occupied nests after October. With the winds and ice of winter the nest disintegrates and vanishes. Hornets never reuse an old nest. In fact they seldom rebuild in a previously colonized area for several years.

With the warming days of spring the cycle begins again.

While Bald-Faced Hornets are formidable when aroused it should be remembered that they're only defending their home. Away from their nest they're meek, inoffensive and nonconfrontational sipping nectar for themselves and hunting spiders for their young. As spider predators they're superb with each colony consuming thousands of spiders a year.

So should you be fortunate enough to have a hornet colony establish itself in one of your shade trees don't panic and call the exterminator or buy cans of toxic waste to deal with the "problem". We once had a colony build in our front yard within feet of a very busy sidewalk. Over the course of the summer neither we nor anyone else had a single adverse encounter with our temporary neighbors and hours of fascination watching them build and expand their house. In fact the vast majority of people passing by (and our street is a major conduit to the local university) probably never even saw it.

The moral of this story is, I guess, that Hornets are good neighbors.

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• More about the Bald Faced Hornet and its nest.

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