by Michael F. Potter, Extension Entomologist
University of Kentucky College of Agriculture
Paper wasps, hornets and yellowjackets are a potential health threat to Kentuckians. Hundreds (perhaps thousands) of people in the United States die each year from allergic reactions to the venom of these insects. Wasps, hornets and yellowjackets are more dangerous and unpredictable than honey bees and should be treated with respect; nests should be eliminated with great care and in a specific manner.
Paper wasps, hornets and yellowjackets construct nests of a paper-like material which is a mixture of finely chewed wood fragments and salivary secretions of the wasps. Paper wasps typically build their umbrella-shaped nests under eaves and ledges. These wasps are not as aggressive as yellowjackets or hornets, and can be eliminated rather easily with a wasp and hornet spray sold at most grocery and hardware stores. These formulations have an added advantage in that they often spray as far as 20 feet.
Treatment of wasps, hornets, and yellowjackets is best performed at night; paper wasps can be eliminated during the daytime provided you do not stand directly below the nest during treatment. Most wasp and hornet sprays cause insects to drop instantly when contacted by the insecticide. Standing directly below a nest increases one's risk of being stung.
Following treatment, wait a day to ensure that the colony is destroyed, then scrape or knock down the nest. This will prevent secondary problems from carpet beetles, ants and other scavenging insects.
Hornets are far more difficult and dangerous to control than paper wasps. The nests resemble a large, inverted tear-drop shaped ball which typically is attached to a tree, bush or side of a building. Hornet nests may contain thousands of wasps which are extremely aggressive when disturbed. The nests are often located out of reach and removal is best accomplished by a professional pest control firm.
A full wasp suit sealed at the wrists, ankles and collar is recommended when disposing of a hornet nest. Treatment can be accomplished by applying a wasp freeze-type, aerosol insecticide or dust formulation (Sevin, or Ficam,) directly into the nest opening. Hornet nests have a single opening, usually toward the bottom, where the wasps enter and exit. It is essential that the paper envelope of the nest not be broken open during treatment or the irritated wasps will scatter in all directions, causing even greater problems.
Following treatment, wait at least a day before removing the nest to ensure that all of the wasps are killed. If hornets continue to be observed, the application may need to be repeated. Experienced pest control operators will sometimes remove a hornet nest which is attached to a branch by slipping a plastic garbage bag over the intact nest and clipping it at the point of attachment. This technique should not be attempted by anyone else and should only be done at night with a wasp suit.
Yellowjackets are another dangerous wasp encountered around homes and buildings. Nests are often located underground in an old rodent burrow, beneath a landscape timber, or in a rock wall or wall of a building.If the nest can be located, it can usually be eliminated by carefully applying a wasp spray insecticide into the nest opening.
Sevin (tm), or Ficam (tm), dust is also very effective provided a handduster or similar type applicator is used to dispense several puffs of the insecticide dust in to the nest opening (an empty, dry liquid detergent bottle, filled no more than halfway with dust and shaken before dispensing works well).
Treatment should be performed late at night after all yellowjackets are in the nest and less active. It's best to pinpoint the nest opening during the daytime so you will remember where to direct your treatment after dark. Approach the nest slowly and do not shine the beam of the flashlight directly into the nest entrance as this may startle the wasps; instead, cast the beam to the side to illuminate the nest indirectly and place the light on the ground rather than in your hand. Similar to hornets, yellowjackets are extremely aggressive when the nest is disturbed. It may be prudent to call a professional pest control company, particularly when access to the nest is difficult.
An Alternative Solution
If the nest is located away from high traffic areas, another option is to wait and do nothing. In Kentucky, wasp, hornet and yellowjacket colonies die off naturally after the weather turns cold, and the paper carton disintegrates over the winter months.
People Who Are Allergic to the Venom
Wasp, hornet and yellowjacket stings can be life-threatening to persons who are allergic to the venom. People who develop hives, difficulty breathing or swallowing, wheezing or similar symptoms of allergic reaction should seek medical attention immediately. Itching, pain and localized swelling can be somewhat reduced with antihistamines and a cold compress.
CAUTION! Pesticide recommendations in this publication are registered for use in Kentucky, USA ONLY! The use of some products may not be legal in your state or country. Please check with your local county agent or regulatory official before using any pesticide mentioned in this publication.
Of course, ALWAYS READ AND FOLLOW LABEL DIRECTIONS FOR SAFE USE OF ANY PESTICIDE!