Now is the time to be alert for nests of yellowjacket wasps, hornets, bumble bees and other social insects. These social insects develop in colonies that start each spring with a single queen. By now colonies should be large enough to notice and control now will prevent the nest from getting any larger and increasing the threat of being stung.
Yellowjackets build paper nests either in the ground, in a log or landscape timber or inside a building wall or attic. Nest openings are discovered by the activity of workers hovering back and forth at the small hole.
Baldfaced hornets make the familiar, large, gray, paper nests seen in trees. The nest is constructed of paper-like material made from chewed wood fibers mixed with saliva. The nest is composed of 3 or 4 tiers of combs within a thick, multilayered outer shell. A single opening at the bottom allows the hornets to fly in and out. Hornet nests are usually located in wooded areas, attached to a tree branch, but may be attached to shrubs, utility poles or house siding.
Bumble bees usually nest under ground in a deserted mouse nest or bird nest. Occasionally they nest in cavities within a wall or even in the clothes drier vent. Bumble bee nests are small compared to honey bees, as each nest contains only a few hundred individuals.
When the nest of a stinging social insect is located in and out-of-the-way location and not likely to be disturbed, it is best left alone. If, however, a nest is located in a "high traffic" area such as along walks or near doorways, control is justified to reduce the threat of being stung.
Nests in walls or in the ground can be destroyed by placing an insecticide dust (e.g., Sevin, permethrin or rotenone garden dust) in the nest entrance during the night. Wear protective clothing and approach the nest with caution. Do not shine your flashlight directly into the nest opening. Control will usually occur within a few days. Retreat after 2 or 3 days if necessary. Do not plug a nest opening in a house wall until you are sure all activity within the nest has stopped. Use "wasp and hornet" aerosol sprays for exterior hornet nests. Read and follow label directions.
This article originally appeared in the July 16, 1999 issue, p. 97.