Roxanne Rutledge, PhD
Extension Specialist, Medical Entomologist
Assistant Professor
UF/IFAS/Florida Medical Entomology Lab (FMEL)
crr@mail.ifas.ufl.edu

Mosquito season has arrived! As people start spending more time outdoors and sending kids off camping and swimming, they become more aware of mosquitoes. Along with awareness, people become concerned about how to best protect themselves from mosquito bites.

Currently, the public is inundated with advertisements for several devices that promise to reduce or eliminate mosquito populations. One model generates carbon dioxide (CO²) that acts to lure the mosquitoes to the device, and then another part of the device collects them into a bag where they will die. Several spin-offs of this model use other "attractants" such as octenol (another chemical attractant for biting insects), to lure the mosquitoes into the trap. These have recently appeared on the market targeting homeowners. These devices retail for $300.00 – $1400.00 for the initial investment. At 21–30 day intervals, the fuel that generates the CO² and the octenol must be replaced at the buyers' expense.

Florida County Cooperative Extension offices are likely to receive phone calls from clientele with questions about the efficacy of these products. Do the devices work? Should they buy one?

Currently, there are no published scientific studies to support the claims from the manufacturers of these products. The CO² baited traps will, indeed, catch mosquitoes - a bag full every night in some locations. But can they "decimate a population of mosquitoes" as the advertisements claim? Reduce West Nile virus transmission to humans? Control mosquitoes in an entire acre? Researchers at the IFAS/FMEL will be working with local homeowners to study the devices this summer.

For now, I offer the following for you to consider and pass along to your clientele to assist them in making an educated decision about spending money on these products.

• Female mosquitoes are indeed attracted to carbon dioxide (CO²). This is the cue they follow to find a "host" (blood-meal). Entomologists have been using CO² as "bait" for years to attract mosquitoes for research purposes. Evaporating dry ice is an excellent mosquito lure. The devices that are on the market take advantage of this known aspect of mosquito behavior and they will capture mosquitoes. When a citizen sees a half-gallon collection bag that is full of mosquitoes, the perception is that the device "works great". Salt-marsh mosquitoes emerge as adults by the millions. One impressively large collection, a "bag full," is a minute percentage of all the host-seeking females and will not likely impact these very large populations.

• There are 77 different species of mosquitoes in Florida. Each species varies in what host they bite, the time of day they feed, and how far they can fly. Not all of the mosquitoes that bite humans are attracted to these traps. An important example of this is Aedes albopictus, the "Asian tiger mosquito," that spends its immature stages in tires, vases, bowls, and other water-holding devices that may be found around the yard. This species is a primary biting pest for homeowners, and one that most citizens in Florida will encounter. This species is not attracted to these advertised traps. The best recommendation for reducing this species is to dump out the water every three to four days or remove the container.

• Advertisements claim that the trap will decimate a mosquito population in 4–6 weeks. The life span of an adult mosquito varies with species and temperature, but populations of many mosquitoes that are the target of these devices will often begin to decline naturally within a few weeks if left alone, particularly if rainfall is intermittent and sooner if mosquito control is conducted in the area. There is no evidence that these traps can play a noticeable role in the decline of mosquito populations.

• Taxpayers who live within a mosquito control district in Florida pay considerably less per year for mosquito control than they would pay for the initial investment and continued attractant supply and maintenance of these traps. For example, in Indian River County, the owner of a home valued at $100,000 would pay about $20.00 per year for mosquito control.

There may be certain circumstances where the mosquito trapping devices can indeed reduce mosquito-biting activity in a small area for a specific time period. Several factors would have to be optimal for this to be true:

• There should be little wind to disrupt the attractive CO² cloud
• The mosquito numbers are manageable to begin with.
• The attractant plume is more substantial than large numbers of people.

As with other such products, the buyer beware attitude is still good advice. The only available "results" of how well these devices work are testimonials from those who have purchased them. Such testimonials do not incorporate controlled studies or proper data analysis. Buyer beware. The scientific results of our testing will be communicated to you as soon as they are available. Right now, though, I encourage you to help your clientele make educated decisions concerning these devices.

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The University of Florida's Pest Alert WWW site at: http://entomology.ifas.ufl.edu/pestalert/