Paper Wasps and Hornets
William F. Lyon
|Common Name||Scientific Name|
|Northern Paper Wasp||Polistes fuscatus pallipes Lepeletier|
|Dominulus Paper Wasp||Polistes dominulus Christ|
|Baldfaced Hornet||Dolichovespula maculata (Linnaeus)|
|Baldfaced Hornet||Paper Wasp|
Paper wasps and hornets may become a nuisance when nesting around homes and other structures where people live, work or play. Although considered beneficial to agriculture, (since northern or paper wasps feed abundantly on corn earworms, armyworms, tobacco hornworms, etc. and hornets on house flies, blow flies, harmful caterpillars, etc.), it is their painful stinging ability that causes alarm and fear. Nevertheless, unless the threat of stings and nest location present a hazard, it is often best to wait for Mother Nature to kill these annual colonies. Stinging workers do not survive the winter, and the same nest usually is not reused the following year, except by the yellow and black dominulus paper wasp, on occasion.
The northern or paper wasp is about 1.9 to 2.54-cm long, slender, narrow waisted with long legs and reddish-orange to dark brown or black in colour. There are yellowish markings on the abdomen (rear body part). Paper-like nests, shaped like tiny umbrellas, are suspended by a short stem attached to eaves, window frames, porch ceilings, attic rafters, etc. Each nest consists of a horizontal layer or “tier” of circular comb of hexagonal (six-sided) cells not enclosed by a paper-like envelope. The ends of the cells are open with the heads of the larvae exposed to view.
Baldfaced hornets are up to 1.9-cm long with black and ivory white markings on the face, thorax (middle body part) and tip of the abdomen. Paper-like nests are greyish-brown, inverted, pear-shaped up to three feet tall with the nest entrance at the bottom. Each nest consists of a number of horizontal layers, stories or “tiers” of circular combs, one below the other completely enclosed by a paper-like envelope as a covering. Also, the cells are not exposed to view.
Life Cycle and Habits
Paper wasps and hornets are social insects, living in colonies containing workers, queens and males. Colonies are annual with only inseminated queens overwintering. Fertilised queens occur in protected places such as houses and other structures, hollow logs, in stumps, under bark, in leaf litter, in soil cavities, etc. Queens emerge during late April or early May, select a nest site and build a small paper nest in which eggs are laid. One egg is laid in each cell. As she adds more cells around the edge, eggs are deposited. Larvae in the centre are older with the younger larvae further out. It is the cells at the rim of the nest which contain eggs. After eggs hatch, the queen feeds the young larvae. When larvae are ready to pupate, cells are covered with silk, forming little domes over the individual openings. Larvae pupate, emerging later as small, infertile females called “workers.” By mid-June, the first adult workers emerge and assume the tasks of nest expansion, foraging for food, caring for the queen and larvae and defending the colony. Remember with paper wasps, the nest is the work of a single female, has a single layer or “tier” of cells and is not enclosed by envelopes. In hornets, the nests usually consist of a number of stories or “tiers,” one below the other and completely enclosed by spherical walls. Each cell may be used for two or three successive batches of brood.
Adult food consists of nectar or other sugary solutions such as honeydew and the juices of ripe fruits. Paper wasps and hornets also feed on bits of caterpillars or flies that are caught and partially chewed before presenting to their young. Hornets may be seen almost any summer day engaged in their winged pursuit of flies.
Paper wasps and hornets have a lance-like stinger and can sting repeatedly. When a paper wasp or hornet is near you, slowly raise your hands to protect your face, remaining calm and stationary for a while and then move very slowly away. Never swing, strike or run rapidly away since quick movement often provokes attack and painful stings. Restrain children from throwing rocks or spraying nests with water. Avoid creating loud noises and disturbance near the nest.
When outdoors, avoid the use of heavily scented soaps, shampoos, perfumes, colognes, after-shaves and cosmetics. Avoid shiny buckles and jewellery. Cover exposed skin and wear grey, white or tan rather than bright colours.
Also, remember that if a paper wasp or hornet gets into the automobile while driving, never panic. It wants out of the car as much as you want it out. Slowly pull over off the road, and open the car windows and doors. Trying to remove or kill a paper wasp or hornet while the car is moving can result in accidents.
Treatment of Stings
After being stung, immediately apply a poultice of meat tenderiser to the wound. If the sting is not deep, this will break down the components of the sting fluid, reducing the pain.
A commercial preparation such as a sting kill swab can be used. Antihistamine ointments and tablets taken orally appear effective in reducing sting reactions. Persons highly sensitive to stings should consider a desenitisation program in an allergy clinic. Consult your physician about medical kits such as Ana-Kit, which contains antihistamine tablets and aqueous epinephrine (adrenalin) administered by injection, a tourniquet and sterile alcohol swabs for cleaning the injection site. Frequently, a bronchodilator material (inhaler) is needed.
Hypersensitive persons should never be alone when outdoors at the peak season of wasp and hornet activity. If stung, help may be needed to start prompt emergency treatment measures.
Chemical control should be a last resort as worker populations are gone after a hard freeze or several frosts. There are literally hundreds of insecticide products in various formulations labelled for wasp and hornet control. Control of these social wasps, although usually not difficult, has its element of risk in being stung. It is best to conduct control operations on nests at dusk or after dusk to avoid being stung, since most of the paper wasps will have returned to their nest. If applications must be made during daylight hours, the use of protective equipment, such as gloves, hat, bee veil, coveralls, etc., will help prevent stings from any airborne wasps.
For control of wasps and hornets that build aerial nests near windows, eaves, in trees, etc., insecticides are formulated in pressurised containers that emit a long, narrow stream of spray 4 to 6 metres. Wasp freeze or wasp stopper compounds, containing highly volatile solvents mixed with resmethrin, pyrethrins, carbamates or some of the newer pyrethroids, produce almost instant knockdown for wasps hit. By approaching a hornet nest, spraying in a sweeping motion, the area can be cleared of guards at the nest, followed by directing the spray stream into the entrance hole at the nest bottom to kill those inside. During the day, this technique does not alarm other hornets returning from the field. No other insecticide needs to be introduced into the nest since all adults present are killed and the immature stages (eggs and larvae) die from lack of care. Usually after one to two days, the nest can be removed carefully. Northern or paper wasp nests are easier to treat.
There are many other insecticides labelled for control including chlorpyrifos (Dursban), diazinon, allethrin, fenthion (Baytex), acephate (Orthene), cyfluthrin (Tempo), cypermethrin (Demon, Cynoff), fenvalerate (Conquer), deltamethrin (Suspend SC), lambda-cyhalothrin (Command CS, Command Pestab) and permethrin (Prelude).
Persons who are especially sensitive to stings should get several competitive cost estimates from reputable, licensed, professional pest control operators who have the experience, equipment and most effective insecticides to get the best job done.
This publication contains pesticide recommendations that are subject to change at any time. These recommendations are provided only as a guide. It is always the pesticide applicator’s responsibility, by law, to read and follow all current label directions for the specific pesticide being used. Due to constantly changing labels and product registration, some of the recommendations given in this writing may no longer be legal by the time you read them. If any information in these recommendations disagrees with the label, the recommendation must be disregarded. No endorsement is intended for products mentioned, nor is criticism meant for products not mentioned. The author, The Ohio State University and Ohio State University Extension assume no liability resulting from the use of these recommendations.
All educational programs conducted by Ohio State University Extension are available to clientele on a nondiscriminatory basis without regard to race, color, creed, religion, sexual orientation, national origin, gender, age, disability or Vietnam-era veteran status.
Keith L. Smith, Associate Vice President for Ag. Adm. and Director, OSU Extension.
TDD No. 800-589-8292 (Ohio only) or 614-292-1868