May 14, 2012 – Which Way For Wasps?
QUESTION:
I'm a PMP in Washington and this year wasps are becoming the pest of the year. What product or products do you suggest along with the best eradication methods to nests that are apparently visible?
ANSWER:
There are wasps and then there are wasps, and I truly believe that it should begin with an accurate identification of just what wasps are on the property. We could really look at all wasps as beneficial, since nearly all of the larger species are predatory or parasitic, either laying eggs on or in other insect larvae such as caterpillars or simply taking entire caterpillars, crickets, and other insects back to their nest to feed to their larvae. Many of these wasps are "solitary" wasps, such as the mud daubers, and they feed on great numbers of spiders, crickets, caterpillars, etc., and pose virtually no threat of stinging. As a solitary wasp they do not defend their nests, and do not tend their larvae beyond the initial building of it and providing a stash of food for their larvae. These kinds of wasps, to the horror of so many homeowners, ought to be encouraged in the landscape, as they provide great benefit and pose little risk.
View past Ask Mr. Pest Control questions.
I'm a PMP in Washington and this year wasps are becoming the pest of the year. What product or products do you suggest along with the best eradication methods to nests that are apparently visible?
ANSWER:
There are wasps and then there are wasps, and I truly believe that it should begin with an accurate identification of just what wasps are on the property. We could really look at all wasps as beneficial, since nearly all of the larger species are predatory or parasitic, either laying eggs on or in other insect larvae such as caterpillars or simply taking entire caterpillars, crickets, and other insects back to their nest to feed to their larvae. Many of these wasps are "solitary" wasps, such as the mud daubers, and they feed on great numbers of spiders, crickets, caterpillars, etc., and pose virtually no threat of stinging. As a solitary wasp they do not defend their nests, and do not tend their larvae beyond the initial building of it and providing a stash of food for their larvae. These kinds of wasps, to the horror of so many homeowners, ought to be encouraged in the landscape, as they provide great benefit and pose little risk.
If the homeowner simply objects to the presence of mud nests on the walls of their house these nests can by physically removed and disposed of, and no chemical applications are warranted. If the homeowner is afraid of solitary wasps that are entering holes in the ground they can avoid the area for a week or so and the female wasp will be finished, or cover that soil or keep it dry to discourage the wasps from digging. Educating homeowners may help many of them to understand and appreciate the benefits they derive from the work of most wasps.
For paper / umbrella wasps, which create the hanging nest that is exposed on the bottom, an effective treatment is simply the use of one of the jet sprays that can treat that nest directly from 10+ feet away, instantly killing any wasps on it and many of the exposed larvae as well. This is best done at dusk when the adult wasps should all be back on the nest, but it still is advisable to wear protective clothing to prevent any angered wasp from getting down the back of your shirt. After spraying and immobilizing the adult wasps the nest can be removed and disposed of. The most common player in this group now will be the European Paper Wasp, which has taken over the country and in some places displaced native species by out-competing them for food resources. This species commonly builds its nests within small cavities - hollow pipe fencing, bird houses, porch lights, under tile roofing, and within small cavities under the eaves. For these you may need to expose the nest if possible and then spray, or use a dust within the cavity to kill the adult wasps.
Yellowjackets are the biggest problem, due to their aggressive behavior when you disturb their nest area, the size of their colonies that can reach 20,000 or more workers (all with stingers and an attitude), and the enclosed paper nest that often is hidden within structural voids or in holes in the ground. If you can directly access the nest itself you can treat into it with a pressurized duster, but absolutely be wearing protective clothing (a.k.a. bee suit, bee gloves, bee hood, etc.) to avoid being stung. Some PMP's take a twisted wire and poke it into the paper nest and twirl it around vigorously to break up the layers inside the nest. This helps expose more of the interior for the dusting operation. You may only be able to find the entry point in a structure and have no access to the nest itself, which poses a dilemma. For this you may dust into the entry opening and hope the workers passing through there carry the dust into the nest.
Interesting is that Termidor SC is labeled for wasps and yellowjackets, and labeled for exactly this kind of treatment - directly into the entry points or voids being used by these insects. This may provide you with the same "transfer effect" that seems to be so effective for ants and termites, as passing worker wasps carry the active ingredient into the colony. I was once told by a yellowjacket and wasp expert that you might achieve some level of "prevention" of paper wasps by treating the surfaces under eaves with permethrin, treating only those surfaces that have a history of these paper nests on them. Be careful to adhere to the label uses on the containers that you buy, since pyrethroid labels will all be changing and become more restrictive for exterior applications.
View past Ask Mr. Pest Control questions.
