Integrated Pest Management Manual
Yellowjackets
The name "yellowjacket" refers to the typical yellow and black
bands of color on the abdomen of a variety of wasps common to North
America and elsewhere. Some species are actually black and white, but
are known by the same name. Yellowjacket management is important because
the vast majority of visitors regard yellowjackets (and other stinging
insects) as a threat to their health and safety, as well as impediments
to their enjoyment of the location.
In terms of management, it is important to remember that all varieties
of yellowjackets are beneficial to the natural environment due to their
predaceous behavior and consumption of large quantities of insect pests.
If a nest does not pose a real, direct threat to personnel or to the
public, it is recommended that you leave it alone.
The following information is intended to provide you with a description
of various species of yellowjackets, their life cycle, habitat, and
nest biology, as well as management issues in monitoring and control
and medical treatment of stings. For more detailed information, you
should consult the recommended reading list or discuss specifics with
an appropriate professional. The medical advice offered is not intended
to replace professional medical care. Be prepared to handle emergencies
resulting from stinging insects by contacting specialists in the area
who can offer advise in an emergency situation. Locate these resources
before the emergency occurs. Someone's life may depend upon the
level of preparedness.
Like any other creature, yellowjackets can be understood, managed, even
enjoyed if you know a little bit about their behavior. Proper planning
can avert most of the problems commonly encountered, thus increasing
everyone's enjoyment of the outdoors.
YELLOWJACKET IDENTIFICATION AND BIOLOGY
Yellowjackets (Vespula, Dolichovespula, Vespa) are social insects
that build enclosed paper nests underground, in trees, or in other structures
above ground. Of the 19 species of yellowjackets and hornets found in
North America, only five are considered pests. They are commonly referred
to as eastern, western, southern, german, and common yellowjackets.
These types are considered pests because they are all scavengers who
come into frequent contact with humans as they forage for food. Remember,
though, that all yellowjackets, including those considered to be pests,
are actually beneficial insects in the natural environment due to their
consumption of large quantities of other insects, many of which are
also agricultural pests.
It is not necessary to identify the species of yellowjacket for purposes
of management; therefore, such information is not included here. If
more information is desired, refer to the bibliography. Akre et al.
1981 provides detailed taxonomic keys to the yellowjackets of North
America.
Newly-produced queens are the only members of yellowjacket colonies
to survive the winter (except in some situations in Florida.) From late
March to May, they emerge from hibernation. Having been fertilized by
males the previous autumn, the queen lays approximately 45 to 70 eggs,
which hatch and become the first generation of workers. The queen continues
to lay eggs, forage, and care for her brood. When the first five to
seven emerge, they function as workers and care for all subsequent offspring.
The queen does not leave the nest again. Workers feed the young, expand
the underground nest by digging, produce paper comb, and protect the
nest. Yellowjackets perform all duties of the nest at all ages. Yellowjacket
workers are not sterile, but are kept from laying and caring for their
own progeny by inhibitory chemicals (pheromones) produced by the queen.
If the queen is lost, workers will produce male offspring.
Colonies grow slowly until mid-summer, when successive worker broods
emerge and growth becomes exponential. Pest species typically have 500-5,000
workers at peak population. Increased foraging activity in areas frequented
by human beings, coupled with a competition-induced aggressiveness and
willingness to sting, leads to a sharp upsurge in the number of stings
in late summer and fall (Davis 1978). By autumn, colony size has begun
to decline. New queens mate and go into hibernation, while males leave
to mate and die outside the colony. With the advent of cold weather,
the old queen and workers die as well. Each year's population of yellowjackets
in any given area will be affected by the weather, and thus will differ
from year to year. Sudden cold snaps in the spring can sharply reduce
populations for the rest of the year.
MONITORING AND THRESHOLDS FOR YELLOWJACKETS
Although scientists have developed very precise ways of monitoring insect
populations, a practical approach tailored to the needs of your facility
seems most advisable. If visitors and employees are not frequently bothered
or stung by yellowjackets, it is reasonable to conclude that your management
system is adequate and little, if any, monitoring need be done. However,
if yellowjackets are becoming a nuisance, you may wish to take remedial
action (as described herein) and develop a monitoring routine.
For example, you could select a specific garbage can (or other site
that appears to draw a large number of the pests) and count the number
of foragers that visit within a certain period of time (10 minutes).
It would be best to monitor at roughly the same time each day. Take
remedial action and see if improvements lead to a reduction in numbers.
If stings have become a problem, you may also wish to keep track of
the numbers of persons stung and correlate these figures with those
resulting from forager monitoring. That is, at the point where stings
are very infrequent (or approaching zero), that number of foragers in
a given time period may be an acceptable number, implying good management
of the facility. On the other hand, frequent complaints from visitors
(or the observation by park personnel of pestered patrons) should be
construed as requiring additional effort. Tolerance is expected to vary
from one location to another. Remember, however, it is the great outdoors--some
presence of yellowjackets is natural.
Contingency Planning for Yellowjacket Problems
Plan for emergency care of sting victims who are dangerously sensitive
to venom. Have first-aid facilities or advice for non-sensitive victims.
Monitor individuals who have received stings until you know they are
safe. Pain or swelling at the site of a sting is a normal, non-threatening
reaction; impairment of breathing, swelling of lymph nodes, dizziness,
fainting, or similar extreme reactions are not normal and require expert
help. Non-allergic individuals may find applications of ice, meat tenderizer
or over-the-counter sting swabs helpful. If your facility wishes to
assist sting victims with such remedies, include them in your first-aid
kit. Be aware that only about 0.4% to 0.8% of the human population is
seriously sensitive (in a life- threatening way) to wasp/yellowjacket
venom. Many of these individuals already know of their allergy and carry
sting kits or wear medical identification bracelets to safeguard themselves.
Although anaphylactic shock can occur in as short as 10 minutes (and
can cause coma or death), delayed reactions may occur up to 20 hours
after the sting is received. (See Akre et al. 1981; Frazier 1976 for
details). Also be aware that many individuals refer to themselves as
"allergic" to stings, but do not present life-threatening
symptoms--rather, they are referring to the normal swelling reaction
one may get after being stung. Be sure that employees know how to question
sting victims to accurately ascertain their reaction history and thereby
determine whether emergency assistance is needed. An information sheet
that may be helpful as a hand-out to visitors is included in this module.
Provide good public educational information on yellowjackets, other
wasps, and bees at your location. To be most effective, these should
include color drawings or photos that can be understood by visitors
who cannot read English. Consider the advantage of making signs in both
English and Spanish, or other languages common among your visitors.
If possible, have knowledgeable staff available to answer questions
that may arise from the information you provide.
If absolutely necessary, destroy structural nests, ground nests, and
aerial nests with approved chemicals. This will be somewhat easier to
do in dark or semi-dark conditions than in daylight. Be sure to dispose
of all chemical containers in an environmentally-sound manner.
NON-CHEMICAL CONTROL OF YELLOWJACKETS
Non-chemical control of yellowjackets is achieved by reducing contact
between humans and yellowjackets in every way possible. Displays, handouts,
and other forms of communicating information should teach the visitor
that stings are mainly avoidable by following certain precautions. Educational
materials should emphasize the positive role wasps play in a healthy
environment.
Sanitation
All refuse containers should be solid ones (no wire mesh, etc.) made
of plastic or metal and equipped with wasp-tight lids to prevent foragers
from gaining access to the interiors. All containers should be periodically
checked for holes, cracks, etc., and repaired immediately. Refuse should
be collected on a regular basis before containers are completely
full. This may entail collection several times a day, particularly in
picnic areas and during periods of heavy use of facilities, such as
on weekends or holidays. Containers should be washed out regularly to
reduce odors that attract yellowjackets. Use steam or soap if necessary,
and hose down surrounding concrete areas as well. Plastic bag liners
aid in sanitation and control of fluids that attract insects as well.
Place trash cans as far as possible from picnic tables to reduce interactions
between visitors and wasps. Monitor garbage cans for foraging wasps
to determine local populations and spot critical areas for improvement.
Provide lids and straws on all soft drink containers sold by concessions.
Be aware that yellowjackets can easily enter the openings of aluminum
beverage cans if not carefully monitored by the user--and can thus present
a hazard if accidentally ingested during the process of drinking from
the can. For this reason, paper cups with lids and straws are safer.
Trapping
Trapping can at best provide only temporary relief in very limited areas,
due to the large nest sizes of many colonies. It should therefore be
considered secondary to the previously-mentioned management strategies.
Funnel traps using synthetic lures such as heptyl butyrate have been
used successfully to capture western yellowjackets to a tolerable degree
(Davis et. al 1973), but lures have not proven successful with the eastern
species. A problem with synthetic lures is their inability to target
only yellowjackets that are presenting a pest problem, while ignoring
those performing their natural beneficial function.
Traps using raw fish as bait have been used to temporarily control Vespula
pensylvanica (Akre et. al 1982). Cut the skin to expose the fish's
flesh and suspend it above pans containing water and a wetting agent
(like dishwashing soap) to reduce surface tension. Yellowjackets visiting
these traps typically cut large pieces of flesh from the carcass and
attempt to carry them to sites where they can chew them into smaller
pieces. In so doing, they fall into the water and drown. Advantages
of this method include ease of construction, effectiveness, and avoidance
of toxic materials. Disadvantages include the need to change the bait
frequently, as yellowjackets will not scavenge spoiled flesh, and the
attractiveness of the bait to dogs, cats, flies, and other wildlife.
Chicken-wire cages can be placed around traps to prevent disturbance
by large animals.
In a 1974 test (Akre et. al 1982), nine traps set in a resort area captured
nearly 1000 foraging workers per week. Trapping combined with improved
garbage management reduced active foragers in the area to tolerable
levels within two weeks.
Biological Control
Biological controls against yellowjackets are not currently known. Naturally-
occurring parasites and predators exist, but have little or no effect
on colony dynamics. Scientists continue to experiment in this area,
giving hope of successful methods for the future.
Mechanical Control
Vacuuming of nests is the chief method employed, using a canister-type
vacuum cleaner. One must be prepared to work quickly and be dressed
with protective clothing (such as a beekeeping outfit). Avoid cutting
into the nest, as this provides more than one exit for the angry wasps.
Be prepared to immediately plug the entrance to the canister bag when
removing it from the vacuum, as the yellowjackets inside will not be
dead. The bag can then be frozen to kill the contents. If nests are
removed from structures, the outside entrance should be sealed up, if
possible, to prevent re-entry.
CHEMICAL CONTROL OF YELLOWJACKETS
Due to the large numbers of colonies and workers usually present in
any area, wide chemical control of foragers is impractical, if not impossible.
However, individual colonies located in hazardous spots can be selected
for destruction by chemical means, if other methods are deemed unfeasible.
Spraying should be attempted only after dark, when all foragers are
back in the nest; in addition, the exterminator should wear a protective
suit and take precautions against inhaling chemical fumes.
New products are continually introduced to control yellowjackets. It
is recommended that you consult with an agricultural supplies dealer
or your regional Integrated Pest Management coordinator regarding products
appropriate for your needs. Do not use more than the recommended amount
and use only for the purpose recommended on the product. Some products
require the services of a certified pesticide applicator. Be sure to
dispose of all empty pesticide containers in an approved toxic waste
facility or container.
Do not use gasoline or other flammable liquids to destroy ground-dwelling
yellowjackets. Doing so poisons the soil and can result in explosions
or serious burns. Most chemical controls for yellowjackets are aerosol
products containing pyrethrins, rotenone, and a cooling agent to lower
nest activity and provide rapid knock-down.
Nests in structures are the most difficult to destroy. Do not simply
plug the hole of a healthy colony, or the workers will chew a new hole
through the wall and possibly emerge into human living space. For suggestions
on how to treat such nests, see Akre et. al (1980) and Nixon (1982),
and consult your regional Integrated Pest Management coordinator on
the most effective way of exterminating a specific nest.
YELLOWJACKET FACT SHEET
Yellowjackets are small yellow-and black-banded wasps that build nests
in the ground or paper-like nests in trees. The colony will reach maximum
size in late summer. Worker yellow-jackets are common around picnic
areas where they forage for food.
| Yellow Jackets are attracted to | Ways to decrease stings |
| Perfumes and other scents | Don't go barefoot |
| Hairspray | Don't swat with your hands |
| Suntan lotion | Use lids on soft drink cups |
| Cosmetics | Put tight-fitting lids on trash cans |
| Sweet food | Empty trash frequently |
In most people, a yellowjacket sting produces an immediate pain at the site of the sting. There will be localized reddening, swelling, and itching. Ice or analgesic creams often relieve the symptoms.
IF YOU ARE STUNG
1. Remove the stinger by scraping from the side (for bees)
2. Apply cold water or ice in a wet cloth
3. Lie down
4. Lower the stung arm or leg
5. Do not drink alcohol
Some people experience an allergic reaction to yellowjacket venom. Allergic (anaphylactic) shock can be fatal if untreated. Symptoms usually occur 10-20 minutes after a sting but may appear up to 20 hours later. If you experience any of the following symptoms after being stung, obtain medical aid immediately.
| Symptoms of Allergic Reactions | What to do |
| Hives | Lie down; victim should not be moved |
| Widespread swelling of limb | Lower the stung arm or leg |
| Painful joints | Apply ice |
| Wheezing | Do not drink alcohol |
| Faintness | Apply a wide cloth tourniquet between sting and the heart (should be able to place 2 fingers under bands); release after 5 minutes |
| Get medical aid |
REFERENCES
1. Akre, R.D., A. Greene, J.F. MacDonald, P.J. Landholt, and H.G. Davis.
1981. Yellowjackets of North America, North of Mexico. U.S. Department
of Agriculture, Washington, D.C. Handbook #552.
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1973. Perimeter traps baited with synthetic lures for suppression of
yellowjackets in fruit orchards. Env. Entomol. 2(4): 569-571.
3. Davis, H.G. 1978. Yellowjacket wasps in urban environments. In
Frankie, G.W. and C.S. Koehler, eds. Perspectives in Urban Entomology.
Internatl. Cong. Entomol. Acad. New York. Chapter 7, pp. 163-185.
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6. Greene, A. 1982. Comparative early growth and foraging of two naturally
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