Mosquito traps are marketed as essential hardware for mosquito control programs, but do they actually do the job?
When homeowners or business owners are suffering from a mosquito problem that impacts their enjoyment and use of outdoor areas it’s a major problem and they will often try anything to solve the issue. After all, a mosquito problem at a hospitality venue can ruin a business! That said, many customers also don’t necessarily want to have regular insecticide spray treatments. As a result, many will try mosquito traps of some sort to reduce mosquito numbers. But do they work?
Generally speaking, there are two types of traps: UV light traps (or bug zappers) and traps that utilise carbon dioxide or another chemical attractant.
Outdoor UV light traps are typically marketed to attract and kill a wide range of insects, including mosquitoes. They are certainly popular with consumers; just go into any hardware store. The reality is that these devices, not surprisingly, only catch insects that are attracted to UV light. Mosquitoes are not attracted to UV light! Just to prove the point the University of Florida’s Medical Entomology Laboratory analysed the collection from one UV trap over a single night. Despite collecting over 10,000 insects, only eight were mosquitoes. The 10,000 or so insects sounds impressive (which can fool consumers), but when you consider the vast majority of these were actually harmless insects and indeed insects that wouldn’t have been attracted to the house but for the light trap, it is a needless level of kill with little benefit.
Whilst we’re talking about traps that don’t work, much like their use as a ‘repellent’ for other pests, ultrasonic devices are also a waste of time.
From a scientific point of view, it makes sense to develop traps that are actually based on known mosquito attractants. Mosquito host location involves a number of factors – heat and movement, carbon dioxide levels, a variety of skin odours and moisture. Of these attractants, carbon dioxide-based traps have proven to be effective. One long-term study in France carried out over a six month period in a small village showed a 70% reduction in mosquito numbers.1 And certainly, these types of traps are used in government monitoring programs as they do attract mosquitoes. But to achieve a significant drop in mosquito numbers (around 70%) you need to use a number of traps in a given area and the traps can be expensive to run. Furthermore, although they may help reduce mosquito numbers, they are not necessarily more attractive than a human standing nearby. Therefore they are only really an option in commercial settings and even then as part of an overall mosquito management program using a range of techniques.
Rather than mosquito traps, area repellents based on releasing pyrethroids into the air are effective, but it depends on their placement relative to the humans needing protection, the wind direction and also the area to be protected.
As a point of comparison, the treatment of mosquito resting areas around the perimeter of the areas to be protected, to create a mosquito interception zone, has been proven to provide a reduction in mosquito numbers of up to 90% within a week of treatment, with suppression of up to 70% six weeks after treatment.2
So, for effective control of mosquitoes, elimination or treatment of breeding sites and treatment of mosquito resting areas are key elements of any management program. In accounts that can afford their inclusion, the use of carbon dioxide traps can supplement these activities and also act as a monitoring system. However, there is a lot of active research on mosquito management options, so watch this space.
1 Poulin, B et al (2017). Mosquito Traps: An Innovative, Environmentally Friendly Technique to Control Mosquitoes. Int J Environ Res Public Health. 2017 Mar; 14(3): 313.
2 Trout RT, Brown GC, Potter MF, Hubbard JL. Efficacy of two pyrethroid insecticides applied as barrier treatments for managing mosquito (Diptera: Culicidae) populations in suburban residential properties. J Med Entomol. 2007;44:470–477.
