Bald-Faced Hornet Nests

Bald-Faced Hornet Nests

Most visitors to Eliza Howell Park never see them, but there are many hundreds of Bald-faced Hornets here every summer. They are a native North American social wasp, not a true hornet, and build new nests each year. They are insect eaters much more than nectar collectors, so are not found on flowers as much as bees.

They do visit flowers more late in the season, however, and that provides the best opportunity to see what they really look like. The white on the face accounts for the “bald-faced” name (they are also sometimes called “White-faced Hornets”).

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Bald-faced Hornets are best known by the nests they make, usually placed in tree branches and hidden in the leaves. In the last couple of years, I have kept a record of each nest that I have observed in the park. I don’t finish my count until sometime in December, when they are more visible with the leaves gone. Since paying closer attention, I have seen at least 10 nests annually – and have no doubt missed a number.

The nests are gray and sort of football-shaped, though more the size of a basketball, typically located high in a deciduous tree.

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Fortunately, most years I find at least one that is low enough to be observed more carefully.

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When these low nests are pointed out during nature walks before frost brings an end to hornet season, participants are often reluctant to approach too closely. It is a reasonable reluctance, since the greatest risk of being stung is from hornets protecting their colony. But it is not a big risk if one remains a few feet away.

The nests are made of paper-like material, wood fibers that have been mixed with saliva. The opening for going and coming is at/near the bottom of the nest.

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Each colony is reported to have, at maturity, 100-400 individuals, made up of infertile female workers, reproductive females, and male drones. And, of course, a queen. Queens are the only Bald-faced Hornets that survive the winter, wintering in a sheltered place in trees or the ground. In the spring each queen that has survived begins to build a nest. She makes a few brood cells, deposits eggs in them, and feeds the larvae. The first brood then takes over nest building, food collection, and feeding.

When the nests are broken open after the hornets are gone, one can see the layers of cells that look like honeybee combs. There are tiers of combs within the thicker outer shell.

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It is likely that more queens survive the winter in mild-weather years. This might account for the large number of nests I noted these last two years, following two mild winters. Or I may just be getting a little better about spotting the nests. It will be interesting to see what the findings are next year if this winter is a hard one.

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