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OSU Entomologist (ret.)
An new insecticide is available that can be used to
prepare bait for control of both aerial and
ground-nesting scavenger yellowjacket wasps. Poison
baiting has many advantages over conventional methods
for control of dangerous wasp nests. It is no longer
necessary, for example, to locate individual nests.
(social wasp) nest
Yellowjackets, or social wasps, build large nests
both above ground (aerial nests; see photo) and below
ground (see Yellowjacket
Wasps for details about wasp biology and nest
building). These nests can contain thousands of wasps
and may become dangerous, especially in late summer
and early fall when numbers peak.
When these nests occur in high traffic areas such as
playgrounds or picnic sites it may be necessary to
destroy the nests. Until recently the only options
were to locate and carefully treat individual nests
with insecticide, or use decoy traps to move wasps
away from human activity.
Baits control the entire
The use of insecticide-laced baits has always been the
preferred way to control troublesome wasp nests on an area-wide
basis. The problem has been that the only insecticide that could
be used to prepare the bait was taken off the market about 10
years ago. Recently, however, a new insecticide has come
along that once again allows for use in baits for control of
yellowjackets. Baiting has a number of advantages over
conventional control options and really no significant
The "theory" behind how baits work is that foraging wasps
locate the insecticide-laced bait and carry some back to the
nest where they feed it to developing brood and the queen thus
destroying the entire colony. Only those wasp species that
scavenge dead animals (see Scavenger
vs Predator Yellowjackets) will be attracted to the bait;
these species tend to be the pests at outdoor events and build
the larger, more threatening nests.
- No need to locate individual nests
- Targets only the scavenger
yellowjacket species, the type that cause the most
- May reduce wasp activity the following year
- Very low environmental impact
- Very low non-target impact; even non-pestifierous wasp
species are not affected
Please read: Social wasps, including scavenger
yellowjacket species, are considered to be beneficial insects
in that they prey on many plant pests. It is only when wasp
activity becomes threatening should control of nests be
considered. These procedures involve obvious risks and should
only be undertaken if you are comfortable working with
concentrated insecticide and are willing to assume
all risks associated with this activity. Read and
follow all pesticide label instructions.
Meat (protein)-based baits generally work best. Sugary baits should be
avoided since these can attract and kill
non-target insects like honeybees.
Bait can be prepared from canned fish such as tuna,
minced meats, canned cat food and so forth. Several
different baits can be tested to find the one that is
most acceptable to your local pest species. A small
amount of vegetable oil can be added as well to
enhance bait acceptance.
The only insecticide that can legally be used to
prepare wasp bait is Onslaught
Microencapsulated Insecticide (see label
below). Unfortunately the label for Onslaught does not
give much detail regarding the mixing of the bait but
1/4 teaspoon per 12 oz of bait is probably a good
starting point. Don't overdo it because too much
insecticide can cause the bait to be rejected by
foraging yellowjackets. This works out to 4 x 3oz bait
placements per 1/4 teaspoon of Onslaught.
Where to purchase wasp bait supplies: Onslaught
Insecticide and wasp bait stations are not available in
home and garden-type stores but can be purchased here (DoMyOwnPestControl).
Bait dispenser (bait station)
The bait dispenser and placement must ensure that only yellowjackets
can access the bait. It
to protect non-target animals from exposure to the
bait. Keep bait placements small, no more than
3 oz, and constructed and placed so that they are
secure. It is against
the law to put pesticides, including yellowjacket
baits, into used food and drink containers.
As an example, one commercially-available bait
station (see link above), costing about $10 each
(w/out bait), looks like a large pill bottle with a
1/2" hole drilled near the top and a string from the
screw-on cap that is used to suspend it from a
support. Wasps enter and exit through the hole
and the cap keeps other animals out. Other designs may
work just as well. Two bait stations per acre should
be sufficient for most situations and dispersers can
be hung from a variety of supports (vegetation, fence
posts, and so forth). Bait needs to be replaced when
it is no longer accepted by worker yellowjackets,
probably every 3 days or so.
Start your baiting program around mid-summer when you
see an increase in foraging yellowjacket activity.
Starting any earlier than mid-summer is probably a
waste of time because of limited wasp activity.
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