Yellowjackets, pros, cons, and
By John Fulton
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[September 25, 2014]
With the fall festival season comes the
onslaught of yellowjackets, and the calls have been rolling in to
the office. Yellowjackets are beneficial insects in the sense that
they pollinate plants and feed other insects and carrion (dead meat)
to their larvae. Many times they will prey on insects that we
identify as pests.
Unfortunately, their ability to sting makes them a considerable
health concern. Yellowjackets alone are responsible for about
one-half of all human insect stings. The stings of social wasps,
such as yellowjackets, have evolved as a defense mechanism. The
only purpose for the sting is to inflict pain. Yellowjackets are
easily provoked and, unlike honeybees, can sting more than once.
They will attack in force if their nest is disturbed. Unless a
person is allergic to yellowjacket venom, stings are rarely life
Yellowjackets are most frequently encountered when they scavenge
for food. Their habit of feeding on nectar and sugar can create
a nuisance. Yellowjackets are attracted to open cups and cans of
soda and other sweet liquids. This year it seems like
hummingbird feeders are also a favorite. They are also attracted
to open cans of garbage, bright flowery clothing, and floral
scented perfumes. All outside garbage cans must be kept clean
and well covered, to reduce yellowjacket problems. Contact with
the wasps can be decreased by reducing these attractions at
picnics and other outings. In situations closer to home, the
elimination of overripe fruit from gardens and orchards will
dramatically decrease the number of scavenging yellowjackets.
Holding gatherings indoors and using screens on windows will
also help avoid yellowjacket problems.
There are a variety of traps on the market that claim to attract
yellowjackets. These traps are baited with the scent of rotting
fruit or other odors equally as appetizing to the yellowjackets.
It is questionable whether these traps can out-compete the
natural and man-made attractants described above. However, it is
certain that through proper sanitation and removal of natural
and man-made attractants, yellowjacket contact can be reduced.
However, in situations where the potential for repeated contact
exists, other management methods may be necessary. These traps
can also attract more yellowjackets if placed close to the home
or patio, so place them to attract the insects away from where
Management of each species of yellowjacket differs because of
their nesting habits. Both species do not reuse their nests,
therefore what was a problem this year may not occur next year.
Caulking cracks and crevices in structures in winter and early
spring, after the nests have died, will prevent German
yellowjackets from constructing nests inside buildings. Openings
to active nests should not be caulked. Chemical control for
ground-nesting yellowjackets consists of drenching the exit hole
with an approved insecticide, such as Sevin, and plugging the
hole with treated soil or cotton balls. Yellowjackets that are
not killed by the initial treatment will be killed by chewing on
the treated cotton ball or tunneling through the soil.
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Yellowjacket entrance holes in buildings can be treated with
approved insecticide dusts. As the yellowjackets walk through
the dust they pick it up on their legs and transport it into the
nest. When yellowjackets groom themselves they ingest the dust
on their legs. It may take up to a week for the colony to die
and repeated chemical applications may be necessary. When the
entrance hole of an active nest is in a building, the hole
should not be plugged with the insecticide or caulked. The
yellowjackets may decide to chew through the soft inside wall
rather than chew through the insecticide or caulking material.
Implement chemical control measures at dusk or dawn when the
wasps are in their nest. Wear protective clothing when
attempting to eliminate the nests, such as long sleeved jackets,
gloves, and pants. Tape the wrists and ankles to the clothing,
to prevent the wasps from getting underneath the clothes. A bee
veil or other enclosed form of face and neck protection should
also be worn. Yellowjackets will defend their nest, so to avoid
being attacked, use a flashlight covered with red cellophane
when applying the insecticide at night, since yellowjackets are
unable to see red.
[By JOHN FULTON, COUNTY EXTENSION
DIRECTOR SERVING LOGAN, MENARD, AND SANGAMON COUNTIES]