 Yellowjacket
Wasps
Yellowjacket
wasps (often mistakenly identified as "bees") may become a nuisance
around buildings. From August through October, when yellowjackets
have built up large populations, they seek food such as carbonated
beverages, cider, juices, ripe fruits and vegetables, candy, ice
cream, fish, ham, hamburgers, hot dogs at picnics and other outdoor
events. Many are attracted in large numbers to garbage cans. Others
fly in and out of nests built around buildings and areas where people
live, work and play, causing fear and alarm. Although yellowjackets
are considered quite beneficial to agriculture since they feed on
harmful flies and caterpillars, it is their aggressiveness and painful
stinging ability that cause most concern. Nevertheless, unless the
threat of stings and nest location present a hazard, it may be best
to wait for freezing temperatures in late November and December,
to kill off the colony. Stinging workers do not survive the winter
and the same nest is not reused.
German
Yellowjacket
The German yellowjacket is distributed throughout the northeastern
quarter of the United States and often nests in wall voids and other
cavities. (Other yellowjackets usually nest in the ground.) Nests
in attics and wall voids are large and workers can chew through
ceilings and walls into adjacent rooms. The nest of the German yellowjacket
is made of strong light gray paper. Colonies of the German yellowjacket
may be active in protected wall voids into November and December
when outside temperatures are not severe.
Problems
with yellowjackets occur mainly when:
- humans
step on or jar a colony entrance
- a
colony has infested a wall void or attic and has either chewed
through the wall into the building or the entrance hole is located
in a place that threatens occupants as they enter or leave the
building or
- in
the late summer months, they search for sweet liquids like ripe,
fallen fruit, soft drinks and sweets at picnics, sporting events
and other gatherings.
Yellowjackets
are sometimes responsible for an infection following a sting. A
contaminated stinger can inject the bacteria beneath the victim's
skin. Blood poisoning should be kept in mind when yellowjacket stings
are encountered.
Control
and Management
Inspection
Sting victims often can identify the location of yellowjacket
nests. 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. A nest high
in a tree should not be a problem unless it is where it may be
disturbed. Be sure to wear a bee suit or tape trouser cuffs tight
to shoes.
Habitat
and Harborage Reduction
Management of outdoor food sources is very important.
- Clean
garbage cans regularly and fit them with tight lids.
- Remove
trash that includes bakery sweets, soft drink cans, candy wrappers
and other food waste several times a day from outdoors trash
bins during periods of yellowjacket activity.
- Where
possible, locate food stands away from dense crowds during the
late summer.
- Clean
drink dispensing machines; screen food dispensing stations and
locate trash cans away from food dispensing windows.
- To
limit yellowjacket infestations in wall voids and attics, keep
holes and entry spaces in siding caulked; screen ventilation
openings.
- If
yellow jackets are entering rooms through windows, window screens
should be installed in windows whenever possible.
Pesticide
Application
When possible, treat after dark; workers are in the nest at that
time. If nests are located high in a structure where there may
be a danger from falls or electrical wires; maintenance staff
who also do pest control may be wise to hire a professional pest
control contractor to treat the nest.
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 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.
Tape or tie off wrist and ankle cuffs 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 falling onto
the colony.
- Have
equipment handy so one trip will suffice.
Application
to Underground Nests
- Insert
the plastic extension tube from a pressurized liquid spray or
aerosol generator in the entrance hole; release the pesticide
as indicated on the label.
- 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 steel wool or copper gauze and dust the
plug and area immediately around the entrance with insecticide.
Returning yellowjackets will land at the entrance and pull at
the plug picking up dust. Any still alive inside will also work
at the dusted plug.
Application
to Wall Voids
- Be
especially cautious when using ladders to get at wall void nests.
Set the ladder carefully and move slowly.
- Approach
the entrance hole cautiously; stay out of the normal flight
pattern.
- Watch
first. Observe whether yellowjackets entering the nest go straight
in or to one side or the other.
- Insert
the narrow diameter plastic tube in the hole in the observed
direction of the entrance and release pesticide as indicated
on the label.
- Dust
inside the entrance and plug it as with underground nests.
- Remember,
German yellowjacket nests may remain active into December.
- Use
care not to contaminate food surfaces.
Control of yellowjackets with traps has not been effective with
eastern species. Spraying trash cans and the outside of food stands
will reduce or repel yellowjackets at sporting events; the treatment
will not last long. Remember, do not contaminate food surfaces.
Follow-up
Ongoing monitoring throughout the active yellowjacket season is
essential when a pest management program is in place at locations
where there are outdoor activities. Whenever possible, screens
should be installed in school room windows and garbage cans should
have tightly-sealing lids.
Back
to Index
|
