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How Mosquito
Magnets Work
There's
no doubt about it -- mosquitoes are a total pain.
They land on you, bite you, suck out some blood and leave behind an itchy welt. In the
United States, however, the rise of West Nile Virus has moved mosquitoes
from the "simply annoying" list onto the "danger" list, and
they are now something to be feared. Disease danger has always been the case in
tropical regions, where the main mosquito-borne parasite is malaria.
There
are different ways to control mosquitoes. You can stay indoors (but what fun is
that?). You can use DEET, but it is a smelly
bother to keep applying it. You can try using things like citronella candles or
torches to confuse the mosquito's sensors. What if, instead, you wanted to get
rid of mosquitoes for good?
The
way to eliminate mosquitoes permanently would be to kill all the mosquitoes in
an area. That way, there are no more mosquito eggs being laid and thus no new
mosquitoes. To kill all of the mosquitoes, you would need to devise the world's
best mosquito trap. In this article, we will discuss the elements of the ideal
mosquito trap and learn how a commercially available mosquito trap like the
Mosquito Magnet® works.
If
you ignore the fact that mosquitoes are so annoying and
dangerous, they really are amazing creatures. Female mosquitoes must find blood
in order to reproduce, so mosquitoes come equipped with finely tuned sensors to
help them locate the blood they need. With these sensors, mosquitoes can detect
carbon dioxide, warmth, certain plant chemicals and
sometimes even sweat chemicals. Using
these sensors, a mosquito can hone in on a mammal very easily. To learn more,
see How Mosquitoes Work.
One
easy way to create a mosquito trap would be to take a cow and place it in your
yard. The cow would act as the attractant for the mosquitoes, because the cow
would give off the chemical signature that mosquitoes crave. A cow is warm, it
releases certain plant chemicals (because it eats grass all day) and it produces carbon dioxide with
every breath. If you had a vacuum cleaner that could suck up
every mosquito that came near your cow, you would have a mosquito trap.
If
you used this trap for several weeks, you would start to make a dent in the
population of female mosquitoes. After four to six weeks, you could probably
create enough of a dent to start to depress the entire mosquito population in
your yard. With the number of female mosquitoes down, there would be a lot fewer
eggs being laid. That, in turn, would mean fewer mosquitoes, and eventually the
population would collapse.
Most
neighborhoods do not allow cows, and standing next to the cow to vacuum up the
mosquitoes would be labor-intensive, but this trap would work. To make a
practical trap, what we need to do is create an artificial cow and an automatic
vacuuming system.
Creating
a Mosquito Magnet
To
create an artificial cow, you need to have three things:
- A way to produce carbon dioxide
- A way to create warmth and moisture
- A way to produce the plant chemicals that cows produce
If
you have these three things, you have everything you need to attract many
varieties of mosquitoes. A machine that
combines an artificial cow with an automatic vacuuming system would make a very
effective mosquito trap.
Several
manufacturers have created such a machine, and one of them is called the
"Mosquito Magnet." The way these machines work is quite ingenious.
The
source of the carbon dioxide in the mosquito trap is propane. Propane is
a gas that contains carbon and hydrogen, so when you burn it you get carbon
dioxide and water vapor. Traditionally, we burn propane with a flame, for
example in a barbecue grill.
Modern
mosquito traps put an interesting twist on the burning process. Instead of a
flame, they "burn" the propane catalytically, using the same idea as
that used in the catalytic converter on your car.
The
propane comes in and hits the catalyst -- a set of ceramic beads or a
ceramic grid coated with platinum. The catalyst converts the propane directly
to heat, carbon dioxide and moisture without actually needing a flame. The
advantage of this system is that you can catalyze very small quantities of
propane over a long period of time without having to worry about the flame ever
going out. In addition, there are no worries about other gases, like carbon
monoxide or nitrogen oxides, being produced by the flame. The lack of a flame
also cuts down on fire risks.
Carbon
dioxide is not enough. To complete the chemical signature you add a cartridge
that contains either octenol (a generic molecule
that simulates plant chemicals) or Lurex (a proprietary
mixture that simulates sweat chemicals). These chemicals act as strong
attractants for different types of mosquitoes. Lurex-type
chemicals work best on imported tiger mosquitoes, while octenol works best on
mosquitoes native to the United States.
By
mixing the chemical attractant with the carbon dioxide and moisture and then
blowing it out into the surrounding air, the trap creates a plume of gas that
mosquitoes find irresistible. They will fly upwind to follow the plume to its
source.
When
the mosquitoes get to the mosquito trap, they encounter a vacuum created by a
fan, just like a vacuum cleaner. The fan sucks in air and the mosquitoes. The
mosquitoes are trapped in a net bag, where they dehydrate and die.
Do
Mosquito Traps Work?
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 that
follow.
Related HowStuffWorks Articles
- How Bug Zappers Work
- How Mosquitoes Work
- How West Nile Virus Works
- Can I get AIDS from a mosquito bite?
- Why do my home and office seem to be infested with gnats in the summer? Where are they coming from?
More Great Links
- About.com Landscaping: Natural Mosquito Repellents
- American Mosquito Control Association: A Primer on Mosquito Traps
- EPA and Mosquito Control
- NBII: Mosquito Control and West Nile Virus
- ScienceDaily: Carbon Dioxide Mosquito Traps No Magic Bullet, Say UF Experts
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