QUESTION:

What is the best insecticide to use and the treatment procedure for mosquito control around homes with lots of landscaping shrubs?

ANSWER:

At a recent NPMA convention the topic of "barrier" treating for mosquitoes by our industry was addressed, and the speaker had participated in some field studies to determine just how effective this kind of pesticide application really is in reducing adult mosquito presence in landscapes. The conclusion was that it could be VERY effective, even providing several weeks of relief from biting adult mosquitoes, although never getting 100% control, so that should not be promised. The customer needs to be told what the realistic outcome will be. Some of the products used in this study were permethrin, bifenthrin, and lambda-cyhalothrin - common trade names of the first products out with these a.i.'s are Dragnet, Talstar, and Demand.

All of these active ingredients performed fairly equally and many other pyrethroids probably could give similar results. The treatment had to be made in the location where the adult mosquitoes rested though, so identifying the mosquito species of concern was important. As they stated, Culex mosquitoes tended to rest higher up in trees, while Aedes mosquitoes were more likely to be resting closer to the ground in shrubbery. If you sprayed the bushes and the mosquitoes there were Culex you would get very disappointing results. So, take the time to capture some adult mosquitoes and use a pictorial key and good magnification to determine which kind you have. Even with mosquitoes proper ID is important.

There are hundreds of products specifically labeled for Mosquito Adults, and you can view the entire listing on PestWeb in our resource found in the Product Documents section - select the "Products by Target Pest" tab, then "Flies.........Mosquitoes", then "Mosquito Adults". Note that many of these products are pyrethrum, and of course pyrethrum kills adult flies quickly. It just offers no residual protection, so if your chore is to quickly drop the population of biting mosquitoes for, say, a lawn party that evening, then a light misting with pyrethrum will be helpful. Combine this with the other steps of treating resting sites with a residual, eliminating or treating larval aquatic breeding sites, and using a mosquito trap to monitor for the populations or the species. There also are Misting systems that can be permanently installed that emit a light pyrethrum mist on timed intervals, although some states are looking at these with an eye to regulating their use.

And, I would be remiss if I did not also mention the role of Source Management in mosquito control, meaning identifying all possible breeding sites on or near a property and dealing with the problem at that level. If you can eliminate the aquatic sites the mosquito larvae must live in or treat that water if you cannot eliminate it, you can prevent the development of all those biting adult mosquitoes, and it is only the adults that bother people. Around a home most of the water resources will be small and can be drained, such as empty containers or old tires on the property, rain gutters full of water, tarps that have captured water, low areas in the soil that could be drained or filled. Nearby sources may be local ponds, irrigation or drainage ditches, or catch basins, and these may be treated with a larvicide in many cases. Be careful treating off of your customer's property though, and you may need to get approval for this from the local public works or other property owners. For larviciding you can use products such as bacteria (Mosquito Dunks) or an IGR (Altosid pellets).

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