When they are set up properly, put in the right place and tuned to the appropriate species of mosquito (with the correct attractant chemical), mosquito traps can be very effective. According to the Mosquito Magnet Web site, the most successful case is that of a U.S. Coast Guard station in the Bahamas. The station had become unusable because of swarms of mosquitoes. Six Mosquito Magnets® captured 1.5 million mosquitoes in six days. Eventually, the population collapsed. Mosquito Magnet: Testing contains a number of cases like this.
When a mosquito trap does not work, often the problem can be traced to either the choice of attractant or the placement of the unit. The trap must be placed upwind from the area where mosquitoes are breeding and living. And the chemical attractant must match the species of mosquitoes living in the area.
Even when used correctly, a mosquito trap takes time. It has to be in place four to six weeks to have a significant effect on the mosquito population. It takes that long for existing eggs to hatch and get captured. Once they have been trapped, the population starts to decline.
For more information on mosquito traps and related topics, check out the links on the following page.