May 29, 2003

 

How Do You Get Rid of Pesky Mosquitoes?

That new mosquito-attracting trap in your back yard may cut the number of mosquitoes or it may attract more than you had before. The effectiveness of the traps is difficult to predict because of the complex way that mosquitoes find their victims and the many other factors involved says a North Dakota State University entomologist.

Traps will kill measurable numbers of mosquitoes according to Phil Glogoza, NDSU Extension entomologist. "The big question is whether traps will produce a noticeable reduction in mosquito population. Our perception on their effectiveness depends on a variety of factors. We have to take into account an individuals tolerance level for mosquitoes, the absolute size of the mosquito population, the proximity, wind velocity and direction and the size and type of breeding habitat that produces the source of re-infestation."

The species of mosquito present can also make a difference, Glogoza notes. There are 43 different species of mosquitoes in the Dakotas and about 200 in the United States. Worldwide there are over 2500 different species.

"It is also important to note that there is a risk that traps may actually draw more mosquitoes into an area than they can possibly catch," Glogoza says. "A great deal depends on trap placement, wind direction and how efficient the trap is at killing mosquitoes."

The process mosquitoes go through to find a meal is not simple, Glogoza notes. "They rely on multiple sensory cues that may be visual, thermal or olfactory. These complex behaviors can explain some of the variations in traps and trapping efficiency."

The traps use attractants that lure the host-seeking female mosquitoes to the trap. Some devices use an impeller fan that draws the mosquitoes into a net, where they are trapped and eventually die. Some traps use a sticky surface to capture the mosquitoes when they land. Others rely on the popular electric grid approach, which electrocutes the pests on contact. In general all these devices require some level of regular maintenance to clean them of their "prey."

A popular trap uses carbon dioxide produced either through the combustion of propane or with a carbon dioxide cylinder. "The plume from the carbon dioxide mimics a human exhaling which attracts mosquitoes and not other insects such as moths and beetles," Glogoza says. "I think people will find it interesting that the carbon dioxide is often combined with 1-Octen-3-ol which is a derivative of gasses produced in the rumen of cows. The combination greatly increases the number of mosquitoes attracted to the trap."

Even if a mosquito trap is used, Glogoza still strongly recommends that repellents be used when outdoors. For more information on mosquito control, protection and health issues such as West Nile Virus, visit the following Web sites:

Mosquito Management in North Dakota
http://www.ext.nodak.edu/extpubs/plantsci/pests/e472w.htm

Centers for Disease Control – Q & A on West Nile Virus
http://www.cdc.gov/ncidod/dvbid/westnile/q&a.htm

Comparative Efficacy of Insect Repellents against Mosquito Bites
http://content.nejm.org/cgi/content/full/347/1/13

Grand Forks Mosquito Control Program
http://www.grandforksgov.com/publichealth/mosqu.htm

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Source: Phil Glogoza, (701) 231-7581, pglogoza@ndsuext.nodak.edu
Editor: Rich Mattern, (701) 231-6136, richard.mattern@ndsu.nodak.edu