Wasps

From: Kenelm Philip <fnkwp@AURORA.ALASKA.EDU>

Subject: Re:hornet nests

The common name 'hornet' strictly applies only to the genus Vesa, which in North America is represented only by the imported species V. crabro (European hornet) found primarily in the northeastern and central eastern U.S. states with scattered occurrence to northern Florida, Mississippi, and the midwest. A large colony may have 1000 workers — more typical would be 200-400 workers.

Both Vespula and Dolichovespula are yellowjackets, although D. maculata is commonly called the bald-faced hornet, and some other species of both genera are white and black (some with red) rather than yellow and black. Both genera may construct subterranean or aerial nests, and a single species may also construct both types of nests. On the whole, Dolichovespula nests tend to be aerial while Vespula nests tend to be subterranean — but that's only a generality. Peak worker populations in Dolichovespula nests range from less than 100 to 700.

Vespula peak worker numbers for annual nests run as high as 5000. However, in warmer areas (Florida, California, New Zealand) some Vespula species form perennial nests, where the workers do not die off in the fall. In New Zealand, one nest of V. germanica was 14 feet 11 inches by 5 feet by 2 feet, and was estimated to weigh 1000 pounds and contain 3 to 4 million cells. No estimate of the number of workers was given, but a perennial nest of V. vulgaris in California was 46 by 40 by 30 inches, and contained four gallons of adults. Four gallons of the larger species V. pennsylvanica would amount to over 60,000 workers, so this nest presumably had between 60,000 and 100,000 workers.

So — the claim that "Hornet nests can house as many as 10,000 individuals..." is actually quite conservative, provided you use a sloppy definition of 'hornet', and refer to perennial nests.

Ken Philip fnkwp@aurora.alaska.edu

P.S. The data above came from 'The Yellowjackets of America North of Mexico', by Akre, Greene, MacDonald, Landolt, & Davis. USDA Handbook No. 552, 1980.

Name: Gilkeson, Linda A. Title: Integrated Pest Management
Coordinator Company: Ministry of Water, Land and Air Protection

Reference Text:

Yellowjackets

Most people know and fear the yellow-and-black striped yellowjacket wasps that are common, uninvited guests to late summer picnics. Their stings are painful and for those people allergic to insect venom, they are dangerous. Many people confuse bees, which are fuzzy and only feed on flower nectar, with wasps, which have shiny bodies and are predators. What most people don't realize is that yellowjackets capture enormous numbers of flies, caterpillars and other insects to feed their young. They have been seen bringing in more than 225 flies an hour to a single nest; one study found that over a three day period, just two wasps collected 20 grams of imported cabbageworms. It is usually only in late summer, when their populations are at their peak and wasps are attracted to plants with ripening fruit or aphid honeydew deposits on the leaves that most conflicts arise between humans and yellowjackets. Although they are touchy defenders of their nests, most stings are a result of accidentally trapping or pinching a wasp. You can avoid being stung by following a few rules:

1. Remove all outdoor food sources attractive to wasps. Feed pets indoors and keep garbage cans tightly covered and wash cans regularly to remove spilled food. Bury fallen fruit and table scraps deep in compost piles and don't compost meat scraps or bones.
2. Watch where you sit or step (don't go barefoot!). Be especially careful to look before reaching into berry bushes or picking fruit. Thirsty wasps are attracted to moisture so be cautious when sitting on or handling wet beach towels.
3. Never swat at a yellowjacket hovering around you — it is a good way to get stung. Instead, quietly move away or let the wasp leave of her own accord. The only exception to this is if you have accidentally disturbed a nest and hear wild buzzing. In this case protect your face with your hands and RUN!
4. Pick fruit in the early morning or evening while it is cool and most wasps are still in their nests.
5. To reduce yellowjacket problems at picnics and barbecues:
   1. Minimize the length of time food is available by keeping it tightly covered until just before it is to be eaten. Clear away scraps and dirty plates as soon as the meal is over.
   2. Serve sweet or alcoholic drinks in covered cups with drinking straws through the lids so wasps can't get inside and then sting you in the mouth as you drink. When drinking out of a can, keep the opening covered with your thumb between sips.
   3. Set up baited yellowjacket traps around the edge of the picnic area or on the end of the table to attract wasps away from the food to capture them. Small disposable cardboard traps or reusable ones made of wood and metal screen are sold at garden centers. They work by attracting wasps to bait placed under an inverted funnel. When the wasps have had their fill and instinctively fly upwards toward the light at the end of the funnel, they are trapped in an enclosed chamber above. In early and mid-summer, 1-2 traps should be enough for most picnics. In August and early September, however, six or more traps might be necessary. For much of the season, the best baits are Spam, ham, fish, cat food or meat scraps. Later in the summer, when wasps need less protein because they aren't rearing their young, sweet baits such as jam, honey or rotting fruit are often more water to kill the wasps. Make very sure they are dead before cleaning out reusable traps.

Removing wasp nests:

Although the number of yellowjackets in late summer invariably prompts many concerned inquiries on how to control them, usually there is little that can be done. The wasps will all die in a matter of weeks as fall approaches. Even if a nearby nest is discovered late in the summer, eliminating it may not have the desired effect because wasps can fly in from up to a mile away. It is never advisable to put out poison baits because children and pets may get into them and because other, beneficial, insects may take the bait and be killed. It is also a terrible idea to pour gas or kerosene into an underground wasp nest where it poisons the soil. If yellowjackets do build a nest in a location likely to cause problems with people or livestock, the best time to remove it is early in the season, while it is still small. This is a job for a very careful person or a professional pest control service. Chemical wasp sprays are available, but if you use them, consider very carefully where the stream of pesticide that misses the nest will land. Always use such products according to direction on the label. Remove an exposed nest that has been sprayed as soon as the wasps are dead. Wear rubber gloves and dispose of the nest to prevent birds from eating the poisoned larvae left inside.

To remove a hanging wasp nest without using chemicals:

First, it is a good idea to get a helper. To be safe, both of you should wear protective clothing from head to foot. Although a beekeeper's suit with hat and veil is ideal, you can assemble a similar suit for the occasion from heavy coveralls, a hat with a wide brim and a length of fine screening. Wear boots with your pants cuffs pulled outside the boot tops and seal the cuffs around the boot top with rubber bands so that wasps can't get up your legs. Wear gloves and pull your sleeve cuffs screening over the hat (the brim should keep it away from your face) and tie it around the neck, over the collar of the coveralls. Make sure there are no openings around the collar or base of the veil. You should wear another layer of clothing underneath the overalls because wasp stingers are long enough to reach through one layer of cloth. To remove the nest, approach in the evening or at night when the wasps are all home and less active because it is cool. Have your helper hold open a large, heavy bag or a box with a tight lid under the nest while you cut the attaching stem of the nest as quickly as possible using a long handled pruning hook, or other tool. When the nest is in the bag or box, close it immediately and seal shut. Kill the wasps inside by putting the whole package in a deep freeze for 24 hr. or by directing a wasp spray into the package through a small hole for several minutes. Don't neglect this last step because wasps can eventually chew their way out of almost anything.

Wasp nests in walls:

Wearing suitable protection as above, spray pyrethrins (fast-acting, short-lived compounds extracted from pyrethrum daisies) into the opening of the nest at night. Repeat applications nightly until no more wasps are seen leaving the hole. Never block up the opening as wasps can chew through wood or follow wiring to the interior of the house. In the fall, when the nest is definitely vacant, caulk or repair the crack to prevent recolonization next year.

Underground Wasp nests:

This is a job better left to a pest control operator, who can dig and vacuum out the nest, however, you can apply pyrethrins sprays as above or pour several gallons of boiling water into the nest. Wear protective clothing as described and be extremely careful not scald yourself with the boiling water.

Life Cycle:

In spring, the mated queen wasp crawls out of her overwintering shelter, fills herself on flower nectar and insects and then builds a nest in a hole of a building. She chews up plant fibers and weathered wood to make a grey papery pulp for the first egg cells. The queen rears this first brood herself, foraging for food and feeding the larvae. In about a month these larvae become adult worker-daughters and take over cleaning, building and feeding chores for the next generation. The wasp population grows and the nest expands all season as the workers add new layers of cells. In late summer the queen stops laying eggs and the last of the brood matures. Among the last generation in late summer are both queens and males that develop in special cells. When they emerge, they mate and the queen crawls away into a hiding place under bark, in an old stump or under litter to spend the winter. The workers and males all die before winter, the nest falls apart and is not reused next year.

Yellow Jacket Control:

Yellow jackets (Vespula spp. — colonial wasps), can pose a severe problem for people when these wasps aggressively seek food. (Remember, though, yellow jackets do pollinate plants, such as squash, and dispose of waste matter and thus are not all bad.) Early in the season meat is preferred; later they focus more on sweets. Normally, they are an annual species, with colonies started in the spring of each year by a single mated and overwintered queen. As the season progresses, nest sizes grow and can contain thousands of individuals by late summer or fall. In mild climates colonies can even overwinter. Effective control measures vary according to the circumstances.

1. At eating areas: In a backyard, wasps can be kept under control by diligent use of traps (next section). Public picnic areas, however, have wasps already locked into the readily available food supply (messy previous picnickers). Bring along a fly swatter and eliminate the early arrivals — yellow jacket species are not aggressive when not near their nest. Wasps do not hesitate to go into soft drink cans or bottles, posing a problem for anyone not paying sufficient attention to their activities before taking another swallow. Neither do they hesitate to ride along on a meat sandwich as it is put into one's mouth. Watch out, also, for wasps attracted to meat covered hands, fingers, or utensils. If one places an effective trap (next section) 20-30 feet upwind from the picnic table, the foraging wasps, when shooed away by picnickers, continue to go upwind past the picnic table and end up in the trap.
2. Remote treatment: Yellow jacket bait traps have been used more than a century, with one basic characteristic in design: Wasps will fly into a funnel (somearial quite small) to get at the bait provided and then cannot get out of the transparent or translucent enclosure that incorporates the funnel. One can buy any variety of ready-made traps with a wide range of effectiveness.
   
   The following two companies (among others) have produced successful traps:
   
   Seabright Laboratories,
   4026 Harlan Street, Emeryville, CA
   94608, (800) 284-7363 or (415) 655-3126;
   
   Sterling International, Inc.,
   P.O. Box 220, Liberty Lake, WA
   99019, (800) 666-6766 [FAX: (509) 928-7313].
3. These commercial traps can become clogged with yellow jackets in a relatively short time during severe infestations, and then one must remove them. The problem then arises that live wasps may still be inside and pose a threat. In that case, one can place the trap in a freezer or an ice chest, wait until the cold immobilizes them, and then empty the trap. Alternatively, the trap can be placed in a paper or plastic bag just large enough to contain it. One can then spray a very small amount of electronic parts cleaner (e.g., Electric Parts Cleaner, CRC, Warminster, PA 18974; (215) 674-4300; Electric Motor Cleaner, Berryman, Arlington, TX 76011), one few minutes. One can also construct a simple and safe trap at virtually no cost - an example follows. Start with a one gallon translucent milk bottle. With a razor blade, cut a couple of small slits downward from one point (three quarter inch across at the bottom), a little more than halfway up the sides. Bend the point so formed inward. Fashion part of a wire coat hanger into a hook at the bottom and thread it through a small hole punctured into the cap so that the hook will be down about halfway to the bottom of the bottle when inserted. Bend the top of the coat hanger piece so that it can be suspended from the lid. Fill the bottle about one-third full of soapy water. Then pierce a small piece of turkey ham, salami, or ham (small enough to go through the bottle opening) with the hook and put the lid, hook, and meat in place in the bottle's neck. Hang the bottle in a tree or bush upwind from the area where wasps are not wanted. You might also dig a hole and place the bottle in the ground so the downwind opening is at ground level (wasps often search along the ground for food). If no gallon bottles are available, a one-liter transparent soft drink bottle should suffice.
4. Nest location known (perhaps with more than one entrance) If one knows the location of a ground nesting colony (e.g., Vespula pennsylvanica), the entire colony can be exterminated quite easily by using nothing more than soapy water. Take care, though, because these wasps are highly defensive of their nest, usually allowing one to get no closer than about 10 feet before attacking. Some people prefer to treat the colony at dawn or late evening, when activity at the entrance is less than in mid-day. Fill an adjustable nozzle spray bottle with water, add one level tablespoon of liquid detergent, and shake. Set the spray nozzle on stream, approach from downwind (also from downslope or protected by bushes, if possible), and nest entrance as fast as possible from a distance of 10-15 feet (practice at a target first to improve aim). Wear full protection, including a beekeeper hat and veil, if possible. Once all activity at the entrance has ceased, pour a bucket of soapy water into the ground through one of the entrances and block all entrances with a shovelful or two of dirt.
5. A take home poison:
   When wasp infestations become severe, you may wish to use stronger measures. To reduce their numbers, one can lace a desired food with poison after yellow jackets become committed to that source of food. With this method, timing and procedure are somewhat critical. Expose marauding wasps to canned cat food, such as a shrimp and tuna mixture. Allow the number of foragers to build up into a "feeding frenzy." Then provide a second dish alongside the first, but one laced with a take home poison. Orthene (20 drops per small can of cat food) or KNOX OUT (trade name for a micro-encapsulated diazinon product; one-half teaspoon per can). Don't attempt to use straight diazinon, or the laced food will be rejected).

Subject: Wasps, Yellowjackets, and Hornets

Wasps, Yellowjackets, and Hornets Fact Sheet No. 19, Revised March 1988 Dr. Jay B Karren, Extension Entomologist

Wasps, yellowjackets, and hornets can become a problem if they are found near humans and domestic animals. These insects may nest around homes, in commercial buildings, farm structures and equipment, in parks and in other areas where people live, work, and play. We usually consider wasps as beneficial because of the number of caterpillars, beetle larvae, flies and other insects that some of these species feed on or use to provision their nests.

Others may play a minor role in plant pollination and thus benefit man. Whenever they become too numerous, nest in close proximity to man's activities or become attracted to food being used by man, some control is necessary.

Control should be initiated by destroying the nest or by applying insecticides to the nest site; however, this can be dangerous.

Some wasps, yellowjackets and hornets become more aggressive when disturbed and especially when something threatens their nests.

Disturb the nest as little as possible when applying insecticides and remove nests after dark when the insects are less active or inside their nests. Wear protective clothing including gloves, long-sleeved shirts, and a bee veil, if available. Tie shirt-sleeves and pant legs tight at the wrists and ankles. When using a flashlight, cover the lens with red cellophane since these insects cannot see red light.

It is important to distinguish between the different types of stinging insects that are commonly called bees, wasps, yellowjackets and hornets. Insects properly referred to as wasps have either social or solitary nesting behavior. Digging wasps and mud daubers are examples of solitary wasps, since individual females construct and provision their nests. As a general rule, solitary wasps are unaggressive even if disturbed and seldom defend their nests. Their sting and venom is used as an offensive weapon to paralyze their prey, which consists of many insects and their relatives. The venom of solitary wasps has anesthetic properties and usually is not a serious problem with man.

On the other hand, social wasps such as yellowjackets, paper wasps and hornets use their jaws and legs to attack and subdue prey.

Workers of the social wasps use their venom as a defensive weapon and often attack in large numbers any threatening animal. The venom is designed to produce intense pain and may cause a dangerous systemic reaction in allergic individuals.

Between 0.4 and 0.8 percent of humans are allergic to social wasp and bee venom. Nearly 80 percent of all serious venom-related deaths occur within one hour of the sting. If symptoms are more serious than localized swelling, reddening and pain or mild headache and fever, a physician should be consulted. Multiple stings are especially dangerous. Some people may develop sensitivity to venom after repeated stinging episodes over a short or long period of time.

Solitary Wasps:

Cicada killers are large (1 1/2 inches long) black and yellow wasps that becomes a nuisance in landscapes when cicadas are present in shade trees. Males cannot sting but buzz around humans and appear dangerous because of their size and wasp appearance. Females will not sting unless forced to do so. Control is rarely necessary for this otherwise beneficial insect. The female may dig galleries in lawns, gardens or flower beds, where she lays eggs and provisions the young with paralyzed cicadas. This nesting activity may damage lawns or vegetable gardens. If control is necessary, sprinkle the pesticide dust into the burrow and tramp the entrance shut with your foot.

Mud daubers are wasps that build small, tube-like nests of mud material under eaves, in attics and under roofs of outbuildings.

Nests are generally provisioned with spiders, which the young larvae feed upon. Adults are about 1 inch long and blackish or iridescent blue-black in color. They have a longer and more slender waist than most other wasps.

Nests can be removed easily by hand with a knife or other object, since the attending female will not try to defend her nest. Even after using pesticides, it's generally a good idea to scrape away the nest and dispose of it to prevent dermestid beetles from feeding on the remains and later infesting other household areas.

Social Wasps

Paper wasps are slender, narrow-waisted wasps about 1 inch long with long legs. They are reddish-orange to dark brown or black in color, often with yellow body markings. They produce small colonies that build tiny umbrellas of a paper-like substance. The nests are usually located in open areas, the small honeycomb of larval cells oriented downward. They are often found under eaves, or in attics and outbuildings freely accessible to the adult wasps.

Care should be taken in removing the nests and applying pesticides because these wasps are more aggressive than the solitary wasps.

The common species of hornet we find in Utah is the large bald- faced hornet. It is about 1 inch long, a blackish species with white markings especially on the front of the head. These hornets construct large inverted pear-shaped, paper carton nests up to 1 foot wide and 3 feet long. The grayish or brownish nest contains 2 to 4 horizontally arranged combs with a round entrance hole at the bottom. Nests may be found hanging under porches, in outbuildings, in trees or even attached to the side of a structure.

There are hundreds of individuals in a nest that become very aggressive when aroused or disturbed. The sting can be very painful. Control is usually left to the professional pest control operator. Even with the proper protective clothing one should be very careful when applying pesticides and removing the nests.

Direct sprays to the nest opening then soak the entire nest. Nests that pose no threat to humans should be left undisturbed since the hornets are beneficial predators of other insects.

Yellowjackets are closely related to the bald-faced hornets but usually build their nests underground. They are generally small, about 1/2 inch long, and colored black and yellow. Large colonies of up to 6,000 individuals build soccer-ball-sized paper nests similar to those of the bald-faced hornet. The nests are commonly associated with old rodent burrows and other cavities in the ground or under objects lying on the ground. Entrance holes may be in lawns, gardens, flowerbeds, creek banks or vacant fields. It is unfortunate that these colonies are often disturbed by walking, mowing and other innocent human activities. When disturbed, yellowjackets are aggressive and can inflict a painful sting repeatedly.

Apply pesticides into the entrance of the nests at night, then plug the hole with insecticide-treated cloth, cotton or other objects. Approach the site with caution since some individuals may be guarding the entrance even after dark.

Sanitation:

Some yellowjackets and hornet species scavenge for meat in addition to preying on live insects. Others are attracted to the sweets and sugars of candy wrappers, soda cans, and pastry deposited in garbage cans. These local populations can be reduced by removing the waste frequently and maintaining tight lids on all trash receptacles. Pesticide strips containing dichlorvos (Vapona or No- Pest Strip), attached to the inside of garbage can lids, will also help to reduce both fly and yellowjacket presence.

Control:

Essentially the same chemicals are registered in Utah for all species of yellowjacket, hornet, wasp, and bee control. Wisdom should be used in how the chemicals are applied. Follow the label directions on the specific brand or formulation. Wasp traps with attractants are available and attractant baits mixed with pesticides (Knock Out) are somearial used as well as spraying the nests, nest sides and nesting areas with pesticide. Chemicals such as dichlorvos (Vapona, DDVP), carbaryl (Sevin), propoxur, (Baygon) and diazinon come in sprays or aerosols for these purposes. Some may also contain synergized pyrethrins or resmethrin. In some cases a dust containing one or more of any of these pesticides may be used. A rapidly volatilizing organic solvent mixed with insecticide products containing synergized pyrethrin (Wasp Freeze) is available in some areas. It quickly freezes the wasps and coats them with a pesticide. In the case of aggressive species this can be very useful. Other products (Baygon, Enforcer, and Wasp and Hornet Spray) containing pesticides directs the spray up to 20 feet in a long, fine jet to the nest site so the applicator can remain at a safe distance.

For those who are interested, the attraction chemical used in some of these commercial traps is heptyl buterate. The least expensive price I have found so far is $52.00 for 100g, offered by PFALTZ & BAUER: (800) CALL-1-PB. [As Cindy pointed out, though, be "EXTRA SUPER CAREFUL not to get any on you or spill it." — From: Adrian Wenner <wenner@LIFESCI.LSCF.UCSB.EDU>

Just as an addition to the comments on yellowjacket trapping — heptyl butyrate is only effective on the western yellowjacket, Vespula pensylvanica. It is not effective on any of the eastern pest species such as V. maculifrons or V. squamosa, or on the German yellowjacket, V. germanica. — From: Rick Fell <rfell@VT.EDU>

From: "Todd Reichardt" <REICHART@cia.com> at internet

One additional note regarding Yellow Jacket lures. Two reports in Pest Control Magazine (within the last 2 years) on yellow jacket control cite Grenadine syrup to be the most effective lure. It was more efficacious than some of the commercially available products and some of the favorites such as Coke and tuna (individually, of course :-)

• see also Safe and Sensible Pest Control for Yellowjackets