a better mosquito trap

The Economist

The following article was taken from the April 19 edition of The Economist "A Better Mosquito Trap"

Battling bugs is little different from other kinds of modern warfare. Knowing your enemy helps a lot, and building better weapons gives you an advantage, too.

The traditional method of dealing with mosquitoes, creating an insecticidal fog, is environmentally unfriendly. It is also unpleasant for people in the area and—most pertinently of all—it is becoming less effective every year as insecticide-resistant strains spread around the globe. The mosquito trap works on a different principle altogether. It tricks mosquitoes into thinking they are about to get a meal: for although the Mega-Catch™, as the invention is dubbed, may not look much like a person, from a mosquito’s viewpoint it behaves like one.

Mosquitoes detect their victims in two ways: from the warmth of the body, and from the carbon dioxide in the breath. Mega-Catch™, despite being a 38cm-high black plastic box, radiates heat and carbon dioxide much as a human body would. The heat is provided electrically, and the carbon dioxide (which is moistened to make it appear even more authentic) is released from a small cylinder of the type used to carbonate drinks.

Once she arrives at the box (only female mosquitoes suck blood; the males make do with plant juices), the hapless mosquito is lured through a slot in the side by a glittering pattern of lights. Like many other insects, mosquitoes are attracted by light. But it has to be light of the correct frequency. This is provided by light-emitting diodes inside the trap. The glittering quality, which seems as alluring to insects as it is to many people, is achieved by making the diodes flash and reflecting their light from a piece of aluminium foil that dangles behind the slot. Once inside the box, the mosquito is sucked downwards by a fan and deposited neatly into a pool of water. There, she drowns—for although mosquito larvae are aquatic, the adults cannot swim.

Besides being efficient (test runs show it can trap as many as 1,200 mozzies a night), Mega-Catch™ is selective. It can be tweaked to operate only when a particular species is active (Anopheles, which spreads malaria, is nocturnal; Aedes, which is responsible for yellow fever and dengue, prefers daylight). In addition, few “non-target” species, which would be killed if an area was sprayed with insecticide, are lured into the box.