CHAPTER 2      

STINGING PESTS

Learning Objectives

After completion of the study of Stinging Insects, the. trainee should be able to

Identify common urban stinging insect pests.

    The insects most beneficial to humans are found in the large insect order Hymenoptera. Not only are the bees and many of their relatives pollinators of flowering plants, including fruits and vegetables, but thousands of species of small wasps are parasites of other arthropods including pest insects. Without these parasites that limit the growth of insect populations, pests would overtake most crops.
    The urban pests of the order Hymenoptera are the stinging insects. Although the first image to come to mind implies danger to humans, these yellowJackets, hornets, and wasps sometimes serve our interest: They feed their young largely on flies and caterpillars.
    Many of these stinging insects are social. They live in colonies with a caste system or a division of labor and overlapping generations ? all offspring of one individual reproductive. Some of these colonies persist for many years (ants, honey bees) and others, like stinging wasps, start anew each year.

WASPS, YELLOWJACKETS, AND HORNETS
    In parts of the United States, particularly in the eastern states, yellowjackets, wasps, hornets and bees are all called bees by the general public. Of course the general public is principally focused on one attribute these insects have in common, their stingers.
    Knowledge of the behavior of these pests is essential to their management; effective communication with frightened or, at best, fearful clients is an important skill technicians must develop. Nests of stinging pests are usually the target for control. Understanding nesting and the make-up of the colony is essential.
 NESTS AND COLONIES
    YellowJackets, hornets and paper wasps are all in the same insect family, Vespidae. The common Paper wasp with its umbrella shaped nest or single comb best demonstrates the basic building pattern of a colony.

PAPER WASPS

Paper wasp queens, like other Vespid nest mothers, is the lone female reproductive, who begins her nest by attaching a thick paper strand to an overhanging structure. She then builds hollow paper cells by chewing wood or plant fibers (cellulose) mixed with water and shaped with her mouthparts.

 When a half dozen cells or so are hanging together, the Queen lays an egg near the bottom of each one. The little white grubs that hatch from the egg glue their rear ends in the cell and begin receiving nourishment in the form of chewed up bits of caterpillars provided by their mother. When they grow large enough to fill the cell cavity, they break the glued spot and hold on their own by their stuffed fat bodies, hanging head down. Mature larvae, then, spin silk caps, closing off the cell, and molt into pupae. This same larval behavior pattern is followed by yellowjackets and hornets also. All are females. Other than their white color, these Vespid pupae look like adults; they develop adult systems, then shed their pupal skins, chew through their silk cell cap, pump out their wings, and take their place as worker assistants to their mother. (Paper wasp queens and workers are the same size; yellowJacket and hornet queens are larger than their daughters.) From Spring on, the queen lays eggs and the daughter workers feed larvae and expand the comb or nest. They do not eat the protein (insect) food they gather for the larvae but get their energy from flower nectar. Later in the season, some of the larvae develop into males and others will become next year's queens. The new males and females mate with those of other colonies, and the fertilized females find hiding places under tree bark or in logs and wait out the winter until they can begin their new colony in the spring. The male Vespids die in winter, likewise the nest disintegrates and will not be used again.

MANAGEMENT AND CONTROL OF PAPER WASPS (Polistes) 

Habitat Alteration

YELLOWJACKETS
    Yellowjacket (with eighteen species in North America) colonies begin with a large fertilized queen; she develops smaller daughter workers and later reproductives just as the Paper wasps, but the nest structure is not the same. Some yellowjacket nests hang in trees and shrubs, and some are developed underground.
 Aerial Nesters
    Several yellowjackets make the aerial football shaped paper nests, commonly called hornets nests. Two of these yellowjackets are common: the Aerial yellowjacket, Dolichovespula arenaria, and the Bald Faced hornet, Dolichovespula maculata.

The Aerial yellowJacket is found in the west, Canada, and east ( but not in the central and southern states). This species begins its nest in March or April and is finished and no longer active by the end of July. Their nests, usually attached to building overhangs are smaller and more round than those of other species. The Bald Faced hornet is larger than the other yellowJackets and is black and white, not black and yellow. It lives along the west coast, across Canada, and in all of the states in the eastern half of the country.

On warm spring days, the large Aerial nesting queen develops a small comb, like the Paper wasp with a dozen or so cells, but she encloses it in a round gray paper envelope. The daughter workers later take over the nest duties, and by mid summer, when the worker population is growing and food is plentiful, the nest is expanded to full size. A full-sized Bald Faced hornet nest consists not of a single umbrella comb like the Paper wasp, but four to six wide circular combs, one hanging below the other and all enclosed with an oval paper envelope consisting of several insulating layers. Bald faced hornets not only gather flies, but are large enough to kill and use other species of yellowjackets for larval food. They attach their nests to low shrubs or high in trees or on buildings. Although Aerial colonies can have four to seven hundred workers at one time, their food gathering habits do not routinely bring them in contact with humans. Large nests are often discovered only after leaves have fallen and the nests are exposed ?? both to view and to nature's elements that finally bring about their disintegration.

Underground Nesters
    The stinging wasp, often identified as a yellowJacket, is black and yellow. Primarily yellow bands cover a dark abdomen. These species are in the genus Vespula.
     They begin their nests like the aerial nesters ?with an enveloped small comb made of wood fiber paper. Only these nests are started in soil depressions, rodent burrows, or in any small hole in the ground that will give protection until workers can develop.
    Once workers begin nest care, they enlarge the entrance hole and expand the nest. Combs are placed in tiers, one below the other. They can be very large; they have firm support from the soil surrounding the ,external envelope. Several species of Vespula make their nests in building wall voids, attics, hollow trees and other enclosed spaces as well as the ground.

Both Aerial and Ground Nesters
    Of the thirteen species in North America, only a few require pest management. These few species have certain characteristics and habits that put them on a collision course with people:

They especially enjoy picnics and football games. One can easily see that these habits put a large number of foraging stinging insects into close association with large populations of humans.

THE WESTERN YELLOWJACKET Vespula pensylvanica

    This is the primary pest yellowjacket in the west and is found from Washington to California. It often builds its nests in rodent burrows, clearing the ground around the entrance and producing a colony of around 5,000 workers. This yellowjacket preys on a wide variety of arthropods but also scavenges. It has been known to drive out loggers, fruit pickers, and campers, as well as food facility customers.

THE COMMON YELLOWJACKET
    Vespula vulgaris Second in importance in the western states, V. vulgaris also ranges across Canada and the northeastern United States. Common in higher elevations, it nests in shady evergreen forests around parks and camps in the western mountains and the eastern Appalachians. This species also is one of the most important stinging insects in Europe.

THE EASTERN YELLOWJACKET
     Vespula maculifrons This common ground nesting yellowjacket is distributed over the eastern half of the United States. Its western border is from eastern Texas north to eastern North Dakota. Workers are slightly smaller than most yellowjackets, but colony size can number around 5,000 or more individuals. The nest of V. maculifrons is dark tan, made of partially decomposed wood and is quite brittle. The Eastern yellowjacket sometimes nests in building wall voids. Most yellowjackets have very slightly barbed stingers but the sting will not set in the victim's tissue like the barbed stinger of the honey bee. The stinger of V. maculifrons, however, often sticks and when the insect is slapped off, the stinger may remain. [When stingers are retained, it cannot always be assumed to be a honey bee.]  Vespula squamosa Distributed from Texas, north to Iowa, and east to the Atlantic coast, this yellowjacket is particularly common in the southeastern quarter of the United States. In Florida, colonies are known to be active for more than one year; these southern colonies remain active later in the summer and build up large numbers of workers and reproductives. The Southern yellowjacket sometimes nests in building wall voids.

THE GERMAN YELLOWJACKET
    Vespula germanica In Europe, German yellowjacket nests are subterranean, but in North America the vast majority of reported nests are in structures. This yellowjacket is distributed throughout the northeastern quarter of the United States. Nests in attics and wall voids are large, and workers can chew through ceilings and walls into adjacent rooms. The nest and nest envelope of this yellowjacket is made of strong light gray paper much like that of the Western yellowjacket Colonies of this yellowjacket may be active in protected voids into November and December when outside temperatures are not severe.

 THE GIANT HORNET
    Vespa crabro The last Vespid to be discussed is the Giant hornet (sometimes called the European hornet or the German hornet). Technically, this wasp is the only hornet in North America, but it did not originate here; it was introduced from Europe. It is found in the northeastern quarter of the United States; it ranges as far south as North Carolina and Tennessee with scattered sightings extending west of the Mississippi River. The Giant hornet is reddish brown and yellow and almost an inch long. It builds its nest mainly in hollow trees, and in wall voids of barns, sheds and sometimes houses. An open window or door is an invitation to hornet workers, and they frequent buildings under construction. Their large combs and envelope are constructed of partially decomposed wood and, like the Eastern yellowjacket, are very brittle. Workers of the Giant hornet capture a variety of insects including bees and yellowjackets to feed their young. Workers also have a habit of stripping bark back from some shrubs
especially lilac. As they girdle the branches, they lick the sap from the torn edge. They will sting humans, and the sting is painful.

MANAGEMENT OF YELLOWJACKETS
    Problems with yellowjackets occur mainly when:

yellowjackets are sometimes responsible for injections of anerobic bacteria (organisms that cause blood poisoning). When yellowjackets frequent wet manure and sewage they pick up the bacteria on their abdomens and stingers. In essence, the stinger becomes a hypodermic needle. A contaminated stinger can inject the bacteria beneath the victim's skin. Blood poisoning should be kept in mind when yellowjacket stings are encountered.

 Inspection
     Sting victims often can identify the location of yellowjacket nests. Where the nest has not been located look in shrubbery, hedges, and low tree limbs for the Bald Faced hornet. Soil nests are often located under shrubs, logs, piles of rocks and other protected sites. Entrance holes sometimes have bare earth around them. Entrance holes in structures are usually marked by fast flying workers entering and leaving. Nests high in trees should not be proble Be sure to wear a bee suit or tape trouser cuffs tight to shoes.

Habitat Alteration   

   When possible, treat ground and aerial nests after dark [Workers are in the nest at that time]. More often than not, because of traditional work schedules, treatment will be scheduled for the daytime. Begin with the entrance hole in view and a good plan in mind.
Wear a protective bee suit. Unless these insects can hold on with their tarsal claws, they cannot get the leverage to sting. Bee suits are made with smooth rip-stop nylon which does not allow wasps and bees to hold on. A bee veil and gloves are part of the uniform. Wrist and ankle cuffs must be taped or tied to keep the insects out of sleeves and pant legs. Move slowly and with caution. Quick movements will be met with aggressive behavior. Move cautiously to prevent stumbling or failing onto the colony. Have equipment handy so one trip will suffice.

Application
    Do. Insert the plastic extension tube from a pressurized liquid spray or aerosol generator in the entrance hole; release the pesticide for 10 to 30 seconds. Resmethrin is most effective. 01 If the pressurized liquid spray includes chemicals that rapidly lower nest temperature (freeze products), be aware that it will damage shrubbery.
    Plug the entrance hole with dusted steel wool or copper gauze. Dust the plug and area immediately around the entrance. [Returning yellowjackets cue on entrance holes using surrounding landmarks and seeing the shadowed opening. They will land at the entrance and pull at the plug picking up toxic dust. Any still alive inside will also work at the dusted plug. Aerial Nests No. Cut aerial nests down and seal them in a plastic bag. [The queen and workers inside will be dead, and larvae will fall out of their cells and die from either insecticide poisoning or starvation. Pupae in capped cells may escape the treatment, however, and emerge later.] Be especially cautious when using ladders to get at aerial nests or wall void nests. Set the ladder carefully and move slowly.

Wall Voids

    Spraying trash cans and the outside of food stands will reduce or repel yellowjackets at sporting events; the treatment will not last more than one day. Honey bees are also killed with this control measure. Remember, do not contaminate food surfaces.
     A synthetic chemical lure (composed of 2,3hexadienyl butyrate) is attractive to the Western yellowjacket Traps with this lure were found to depress wasp populations successfully in a peach orchard and in some western campsites. They are ineffective with eastern species.
Follow-Up
    Ongoing monitoring throughout the active yellowjacket season is essential when a pest management program is in place at parks, recreational areas, zoos and other outdoor activity areas.

HONEY BEES Apis mellifera

    The honey bee was introduced into the United States in Colonial America. Honey bees are highly social insects and communicate with each other, relaying direction and distance of nectar and pollen sources. Bees make combs of waxen cells placed side by side that provide spaces to rear young and to store honey. 'Me bee colony lives on the stored honey throughout winters, and therefore, can persist for years.
    When colony populations are high, the queen may move part of the colony to new harborage. Bees swarm at this time, usually finding hollow trees to begin their new colony, but they occasionally work their way into building wall voids.
    A honey bee colony in a house wall can cause major problems. The bees can chew through the wall and fly inside. Their storage of large amounts of honey invites other bees and wasps. Their detritus (e.g., dead bees, shedded larval skins, wax caps from combs and other material) attracts beetles and moths.
     When a bee colony is found in a building wall, it must be killed. Killing can be accomplished in the same way as killing yellowjackets in wall voids is done. Listen to the bee noise from inside rooms to locate the exact position of the nest in the wall to assure that the whole colony is treated.
     After the colony is dead, remove the nest. If the nest is not removed, the wax combs, normally cooled by the bees, will melt and allow honey to flow down through the walls. Honey stain can never be removed; the walls will have to be replaced. As well, the freed honey attracts robber bees and wasps. The comb wax will attract wax moths that may persist for several years. The dead bees attract carpet beetles.After the colony is killed the entrance hole should be caulked or repaired to prevent further bee infestation.

PUT BUMBLE BEE PICTURE HERE

THE AFRICANIZED BEE
    The Africanized bee is the same species as the European honey bee kept by beekeepers all over the United States. Introduced into Brazil from southern Africa, it is adapted to longer warm seasons than are northern honey bees.
    It is thought that this bee will advance as far into the northern temperate region as it has into the southern temperate region. If this is true, Africanized bees will be distributed north in a line that will reach from southern Pennsylvania, west to Seattle, Washington.
     Africanized bees do not store as much honey to take them through the winter as honey bees do. They have smaller colonies and tend to swarm more often. Smaller swarms allow colony development in smaller cavities. In South and Central America, Africanized swarms settle in hollow trees like northern honey bees; they also colonize in rubber tires, crates and boxes, wall voids, abandoned vehicles and other protected places that abound in urban areas. Worker bees tend to mob intruders. The urbanized Africanized honey bee presents a new management challenge not only to beekeepers but to urban pest management technicians.

CARPENTER BEES Xylocopa
    Carpenter Bees are not social insects; they live only one year. The most common Carpenter Bee, Xylocopa virginica, is distributed throughout the eastern half of North America. This bee is a large insect with a hairy yellow thorax and a shiny black abdomen. Superficially, it resembles yellow and black female bumblebees, which are social and more closely related to honey bees. Western Carpenter bees are also large, shiny, sometimes metallic, and are shaped like bumble bees.
    Carpenter bees bore in wood and make a long tunnel provisioned with pollen and eggs. They prefer to enter unpainted wood and commonly tunnel in redwood and unpainted deck timber. They will also go into painted wood especially if any type of start hole is present. New females reuse old tunnels year after year; they are also attracted to areas where other females are tunneling. Egg laying and tunnel provisioning occurs in the spring. Males hover around the tunnel entrance while the female provisions the nest and lays eggs.
    Males dart at intruders belligerently but they can do no harm; they have no stingers . Since these bees ate not social, there is no worker caste to protect the nest. Stings of females are rare.
    New adults emerge after the middle of summer and can be seen feeding at flowers until they seek overwintering sites, sometimes in the tunnels.

Habitat Alteration and Pesticide Application
    Carpenter bees drill into the end grain of structural wood or into the face of a wooden member, then turn and tunnel with the grain.
    Dust tunnels or inject with pressurized liquid insecticide. Insert a dusted plug of steel wool or copper gauze in the tunnel; fill the opening with caulk, wood filler, or a wooden dowel. [A dusted plug stops new adults who otherwise would emerge through shallow caulking.] Caution should be taken, especially if technicians are working on ladders and if they are not experienced with these rather harmless bees.

MUD DAUBER WASPS Family Sphecidae
    Mud Dauber wasps are not social wasps like Paper wasps. They are in a different family. Many paralyze spiders to provision mud cells built to enclose eggs, larvae and pupae. The mud cells form long clay tubes or large lumps. The wasps are slender; they are shiny black or brown, orange or yellow, with black markings. Many have long slender thread waists.  Like Carpenter bees there is no protective worker caste; these wasps are not aggressive; they will not sting unless pressed or handled. Mud Daubers place their mud nests in protected places like electric motors, sheds, attics, against house siding and under porch ceilings. So many wasps congregate at the same site to construct the mud nests that later removal of the nests and repainting is often expensive.
Habitat Alteration and Pesticide Application
    Mud daubers are killed easily with aerosol contact sprays. Scrape away mud nests, and cover problem areas with a good quality smooth paint. Nesting should be discouraged on porticos and high porches of historically important buildings.

CICADA KILLER WASPS Family Sphecidae Sphecius speciosus
    Cicada killers are very large yellow and black relatives of mud daubers, however they do not look like mud daubers. More than one inch long, they look like "monster" yellowjackets. Pest Management Cicada killers can be ignored by those who accept an explanation of their harmless nature. Each wasp,                                                being a female, has a stinger; each can sting. Due to their size and fierce looks, however, stings are extremely uncommon. When there is undue worry about these huge wasps, open soil burrows can be dusted individually; the female will be killed when she returns.

SUMMARY
   Stinging insects are included in the very large order Hymenoptera. Hymenoptera undergo complete metamorphosis and thousands of species are parasites of other insects. When they parasitize pest insects, man lists them as beneficial insects; in many instances they are encouraged, protected or reared and released for their pest suppression qualities. Many species of Hymenoptera are social, including stinging insects such as yellowjackets, paper wasps and honey bees as well as the ants. Stinging social insects (with the single queen) can be very aggressive because there are many workers that can be used to protect the hive and even expend their life doing it. Stinging, non-social hymenoptera such as mud daubers, cicada killers and carpenter bees tend to be non-aggressive and are usually single, fertile females or queens that do not have a colony or a protective caste with the individuals that can be expended.

STUDY QUESTIONS FOR MODULE TWO CHAPTER TWO STINGING INSECTS

1. Describe the two types of nesting habits of yellowjackets.

2. Describe the nesting habits of the paper wasps, Polistes.

3. Describe the nesting habits of mud dauber wasps.

4. What makes an insect a "social insect?"

5. Describe pest management procedures for a stinging insect problem where stings and specimens were the only clues provided by the client.