Darrell Blackwelder

July 16, 2004

            Yellow jackets have unfortunately made an early appearance this summer. Cooperative Extension has received a number of calls about yellow jackets and how to eliminate them.  Yellow jackets, as small as they are, can deliver extremely painful and often deadly stings.

            Yellow jacket stings are often confused honeybee stings; honeybees have barbs on their stingers and can only sting once. Yellow jacket stingers are similar to a wasp or hornet with the capability of delivering more than one sting. These insects can control the amount of venom injected, therefore not all stings are alike. Some stings may only itch for a few hours; other stings can swell and be painful for days.

            The small insects' reputation for delivering a powerful sting may also be lethal to those with allergies. Approximately 50% of all people who die from bites of venomous animals (wasps, snakes, spiders, etc.) succumb to wasp stings.

            Pain by stings of yellow jackets is due to the effect of biogenic amines that include histamines. What is needed to counteract the pain and effect of these histamines, are antihistamines. Wash the area stung with soap and water, and then apply an antihistamine preparation. There are antihistamines available (non-prescription such as benadryl) that can be taken orally.

            Yellow jackets are most active during the mid-day foraging food and cellulose for the construction of the nest. Yellow jackets are somewhat beneficial since they feed on small adult insects and larvae for their source of protein. The insect’s source of carbohydrates is nectar and honeydew secreted by aphids, scales or other insects.

            Closely related to wasps and hornets, these creatures choose to make their home in underground paper nests. Nests can also be found in flowerpots and other containers resting on the ground or the side of a building. The nests are abandoned each year in the fall. The combs were found vertically in loose soil like a fresh pancake.

            Yellow jackets are highly agitated by excessive noise and vibrations. These creatures defend to the death their territory against lawn mowers, weed trimmers, chain saws and other types of power equipment.

            A few yellow jackets survive the winter as mature fertilized queens. When the weather warms in the spring, the queen selects a nesting site and builds a single comb. Over wintering queens forage for food and feed the first larvae while newly hatched workers enlarge the nest and tend the young much as a colony of honeybees. Underground nests often develop into several layers of comb during the summer.

            Future queens and males are produced for next year’s colony in late summer. After mating, the males die and the females seek a suitable site to over winter.

            The entrance to the underground nest is a single hole or cavity about the size of a quarter. Workers, tirelessly migrate in and out of the single entrance during the day.

            The best time to treat an underground nest of yellow jackets is late evening or early morning when the yellow jackets are quite in the nest. Wasp and hornet sprays capable of delivering a straight stream of insecticides work best in destroying the insects' nest. Point the steady stream to the entrance hole and empty an entire canister of the insecticide into the entrance hole. Sprays that contain ether are effective and quick.

            Cover the hole immediately to encapsulate the vapor, insuring a complete kill. Yellow jackets should be dead within 24 hours after an application of the aerosol insecticide.

            More detailed information about yellow jackets can be found at www.ces.ncsu.edu/depts/ent/notes/Urban/horn-yj.htm or www.santarosa.edu/lifesciences/lifehist.htm

Darrell Blackwelder is an agricultural agent in charge of horticulture with the North Carolina Cooperative Extension Service in Rowan County. For archived garden columns or other information, visit the Rowan County Master Gardener web site at www.rowanmastergardener.com , e-mail Darrell_Blackwelder@ncsu.edu