Vespid wasps, such as paper wasps (Polistes spp.), hornets and yellowjackets, are active outside the nest during daylight hours. Nearly the entire colony is in the nest during evening and nighttime hours, although some workers may be stranded away from the nest and will not return until morning. Control measures for hornets and yellowjackets should be attempted during nighttime hours when the whole colony is in or on the nest. Polistes nests can usually be treated during daytime because these wasps are not as aggressive in their nest protection behavior as hornets and yellowjackets.
There are many insecticides labeled for controlling vespid wasp colonies when applied into or onto the nest. The difficulty involves making the treatment without being stung. If applications must be made during the day our technicians may sometimes wear personal protective equipment (PPE) such as boots, heavy coveralls, veiled headwear and heavy gloves. Many traditional suits used by beekeepers will not offer sufficient protection against wasps, particularly aggressive attacks by bald-faced hornets.
All PPE are carefully secured in such a fashion that wasps cannot slip under cuffs or other areas of clothing. When working around yellowjackets and bald-faced hornets, many professionals wear an extra layer of heavy cotton work clothes under their wasp suits so no stings can penetrate through clothing. We may use plenty of masking tape wrapped around bottoms of pant legs and sleeves and around collar. If these stinging insects get under protective suit, a very dangerous situation can arise in terms of basic safety, especially if PMP is working high above ground on a ladder.
For Polistes nests, an aerosol spray of one of the many fast-acting wasp killer aerosols that contain permethrin or some other pyrethroid insecticide can be used. These sprays can be applied via use of a long pole, where the can is positioned at the top of the pole and activated by use of a lanyard . Alternatively, a dust of carbaryl or one of the pyrethroids can be applied directly onto the exposed nests for a slower-acting insecticidal approach.
After killing the colony with the initial insecticide application, it’s important to scrape or knock down and remove the nest so as not to attract dermestid beetles at some later time and to keep wasp pupae from possibly re-establishing the worker force. We need to be sure that a spray or dust residue of a residual insecticide is left in the nest area to ensure that any worker wasps not present at the time of initial treatment will be killed later.
The most difficult problems in wasp control are generally those that involve large aerial nests of yellowjackets (including bald-faced hornets) and ground or structural nests of yellowjackets. Aerial nests are often not readily accessible from the ground. It would seem that the easiest way to treat such a nest would be to spray it from the ground with a power sprayer, but this is generally not advisable: The force of the spray stream will often break open the carton nest envelope and scatter the nest and excited wasps in all directions. Although the nest will be destroyed and many wasps eventually killed, a number of workers will escape and continue to cause problems for your client on the following morning. The absence of the nest and presence of insecticide seem to aggravate these stragglers, so they will have a greater tendency to attack and sting nearly any moving object.
Control of aerial nests of hornets and yellowjackets should be attempted only while wearing a full wasp suit or equivalent personal protective equipment (PPE). If ladders are needed, this work should be conducted only using heavy-duty ladders in good condition and proper ladder safety procedures. Treating or removing aerial wasp, hornet or yellowjacket nests is no time to be using a flimsy, unsafe ladder.
To accomplish fast wasp knockdown and killing action, we can direct a specialized aerosol formulation or dust application into the nest opening. A liberal amount of material should usually be applied - up to one large can of aerosol or 4 tablespoons of dust per label directions. Within a few hours, or certainly by the next day, all the colony members should be killed by this initial application. Before nest removal on the next day, a few seconds of aerosol spray should be directed into the nest entrance to ensure all wasps have been killed. The nest should then be removed if possible.
Aerial wasp nests can even be removed in-lact and without the use of insecticide if the professional wears PPE and simply slips a large, heavy plastic garbage bag over the nest and removes it (sealing the bag after the nest is free of its attachment point). A quick dusting of the nest area will serve to kill over the next day or so any stragglers not removed with the nest. This removal need not be dangerous as long as a full wasp suit is worn and carefully sealed. Goggles or eyeglasses are necessary when working around a bald-faced hornet’s nest to prevent the hornets from spraying venom through the veil of the wasp suit and into the eyes.
After securing the nest in the garbage bag, we can kill the colony by simply leaving it in sunlight or some other warm area because wasps cannot withstand high temperature conditions for any length of time. Alternatively, we can freeze the nest in a freezer for a day or so or burn it in an incinerator.
To safely and effectively control ground-nesting yellowjacket nests, it is recommended to do so at night to minimize safety concerns.
When approaching the nest at night, we use a spotlight or flashlight from a safe distance to avoid attracting the wasps. It is essential to wear protective clothing and approach the nest slowly and carefully. The best way to kill the colony is to use a hand duster with insecticide, such as carbaryl or pyrethroid dust, applied directly into the hole. We can seal the hole with a rag or steel wool as the dust is applied, and more dust can be used around the nest entrance to kill returning workers.
For yellowjacket nests in structures, we can approach the entrance at night and apply insecticide into the entry hole. Never plug the entrance from the outside as the workers may escape towards the inside, creating a stinging hazard. A follow-up visit the next day is necessary to ensure all activity has ceased.
If a carton nest of yellowjackets is accessible, it should be removed, or the homeowner should be advised to do so, even if some carpentry work is needed.
Yellowjacket nests can attract carpet beetles and other pests, which can infest the home. When treating honey bee infestations in a structure, the success of the treatment largely depends on the steps taken before applying insecticides. We explain the situation to the customer in detail, including the possibility of odor, staining, and rotting bees. The removal of the nest and honey and sealing the entrance hole is necessary to prevent the bees from returning.
For voids within walls, a dust formulation of carbaryl or pyrethroids is recommended to avoid spotting or staining of inside walls. Dust should be blown into the entrance hole used by the bees, and if the nest is reachable by drilling a hole into a wall, treatment can be done from the inside without the need for protective clothing or a ladder, but the possibility of bees entering indoor areas should be considered. It is best to treat at night when bees are less active and to wear personal protective equipment. After applying the insecticide into the entry hole, residual insecticide spray or dust should be used on surfaces around the nest entrance.
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