By Donald Lewis
Entomologist
Iowa State University Extension
One of the more interesting "conversation pieces" to display in a home, natural history museum or office is the nest of the baldfaced hornet. The baldfaced hornet is a social wasp that constructs the familiar large, gray, paper nests attached to a tree branch, shrub, utility pole or house.
Baldfaced hornets are large, black insects about 7/8 of an inch long with white to cream-colored markings on the front of the head and at the end of the abdomen. Like all wasps, bees and ants, hornets have a complete life cycle of four stages: egg, larva, pupa and adult. The larva is a legless grub reared within cells in the nest. Hornets are beneficial predators that feed on other insects, particularly flies.
The hornet’s nest is a marvel of nature’s engineering. The nest shelters the colony through wind, rain and hail and provides a secure location for raising offspring. The nest is constructed of paper‑like material made from chewed wood fibers mixed with saliva (technically known as “wasp spit”). The nest is composed of 3 or 4 tiers of open-celled combs within a thick, multilayered outer shell. A single opening at the bottom allows the hornets to fly in and out.
Each colony of social wasps such as hornets, yellow jackets and paper wasps lasts only one year. Each nest is built from scratch each year. The previous year’s nest can not be reused and in the case of hornets, disintegrates quickly in late fall winds and rain.
Queens are the only members of the colony able to survive the winter. In April or May, the queen selects a suitable location, constructs a small, round nest the size of a tennis ball and begins laying eggs, gathering food and raising her offspring. The first offspring of the queen are all sterile daughters. These workers take over the duties of enlarging and maintaining the nest, foraging for food and caring for the larvae while the queen retires to only produce more eggs.
Peak worker population is 100 to 400 hornets by the end of the summer. Males and new queens produced in late summer leave the nest to mate. The fertilized queens hibernate and begin the cycle again the following year. The remainder of the workers, the old queen and the males die of old age or freezing temperatures, whichever comes first.
Unless a hornet’s nest is built in a high-traffic area where the threat of stinging is unacceptable, they should be left alone. However, if control is warranted, use one of the several aerosol products specifically designed for this purpose (“wasp and hornet killer,” etc.). Colonies should be exterminated at night, if possible, when workers are least active and the maximum numbers are at the nest.
But rather than control the hornets and risk ruining the nest, why not take it down and hang it up for display. I can attest; they are great conversation starters.
The easiest method of collecting a nest is to wait until after the hornets have abandoned the nest in the fall (after the first hard freeze or by late October). Collect the nest as soon as possible because exposed, unprotected nests are subject to destruction by wildlife and weather. There may be few, if any hornets in a nest collected in late fall. If you feel the need to be extra-cautious, leave the nest in a garage or porch where it will be protected from the weather until mid-winter. Then bring the nest indoors for display. Leaving the nest in the garage also eliminates the slight risk that the carcasses of hornets and larvae that remain in a collected nest may produce a mild odor before they completely dry up.
It is not necessary to treat the collected nest in any way. Varnish or preservative is not required. The nest will last almost indefinitely if it is suspended in a dry location where it will not be damaged by handling or vibration. Just hang it up, sit back, admire and enjoy!
Contacts:
Donald Lewis, Entomology, (515) 294-1101, drlewis@iastate.edu
Jean McGuire, Extension Communications and Marketing, (515) 294-7033, jmcguire@iastate.edu