Jun 14, 2011 – BakeABug In A Biscuit

QUESTION:

I have mosquitoes that are getting into a bakery. There is a little swamp on one side of the building. I am wondering if these pests are attracted to light, and I would like to place a couple of fly lights and do a ULD monthly or something like that. Please advise.

ANSWER:

Let's do a little math on mosquitoes first, and the most important number is that it takes only about 1 week for mosquito eggs to become adult mosquitoes, give or take a few days depending on the species and temperatures. While the monthly fogging would give immediate relief from biting adult mosquitoes in that area it will lose its effect quickly and new adult mosquitoes would quickly repopulate the area. This may be appropriate if this bakery is having some outdoor function where you need to knock down the mosquito numbers temporarily, but fogging is not a good overall control.
Adult mosquitoes are drawn to UV light, but not strongly, so UV lights are only partially effective in attracting and capturing them. Plus, many mosquitoes are day or dusk fliers when natural light outdoors will diminish the effectiveness of the UV light. Mosquito traps generally employ both UV and carbon dioxide, as the CO2 is a much stronger attraction for these blood feeders. Even then the traps are best seen as monitors rather than as a control device. However, each step you take does capture and kill adult mosquitoes, dropping their overall numbers. If you do use UV light traps it might be best to have them installed away from the building so you do not attract night flying bugs TO this structure.

Another chemical option is what is referred to as a "barrier" treatment, and this involves the use of residual insecticides such as pyrethroids, applied with a sprayer capable of treating the trees and shrubbery in the area, as well as other adult mosquito resting spots such as under the eaves or any other structures where they can find shaded shelter. Some studies were done that concluded that several weeks of good relief from biting mosquitoes could be gained by treating in this manner. It may be important to capture some of the mosquitoes and have them identified, at least to genus level. The different kinds of mosquitoes choose different places to rest, and if you have a tree inhabiting mosquito such as some of the Culex, and fail to treat up into the upper foliage of the trees, you could miss the adult mosquitoes altogether. Other kinds may prefer lower shrubbery or other ground level places to rest.

However, if you have any control at all over that adjacent swamp this is where your focus should be. It is likely that this habitat is a major breeding area for the mosquitoes, and the best mosquito control involves "source reduction" - killing the mosquitoes in their larva stage rather than waiting for them to become biting adults and then swatting them at this problem stage. There are several excellent larvacides available that can be used in aquatic habitats to kill mosquito larvae but cause no harm to other animals that use that water. These can be easily applied by hand or with equipment, depending on the area of water to cover, and some may last 30 to 90 days once applied. They include IGR's such as Altosid or bacteria such as Mosquito Dunks or BTI Briquets, and also surface oils such as MasterLine Kontrol Larvacide. Of course, if this little swamp is not an environmentally sensitive aquatic site, but just an area of captured rainwater, perhaps it could be drained permanently and the problem resolved forever.

So, for immediate relief the fogging is good but provides no residual. Barrier treatments provide several weeks of relief but need to be reapplied during adult mosquito season. UV and CO2 traps will help reduce numbers but are best for monitoring. Larval control by treating the breeding sites is the best technique if you are permitted to treat that aquatic habitat.

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