Lab Times Summer Read (7) – Mosquitoes and Limburger Cheese

(August 1st, 2017) Digging deep into our archive, we found quite a few gems from the past, worth a second read. Here's some Incredible Science from the secret archives of the IgNobel committee, from 2006.

There are many assumptions about what mosquitoes are really partial to; for instance sweet blood, stinky feet and underarm perspiration. And, as every tropical traveller well knows, there is significant regional variation between the different species of stinging mosquito. “Autan”, a German anti-bug lotion, won‘t necessarily help against Vietnamese mosquitoes, whereas in Europe the perfumed mosquito coils from the Phillipines might smoke out your entire home for hours without impressing a single one of those infernal little mites.

In an effort to put an end to the annual summertime terror once and for all, the Mosquito and Fly Research Unit of the US Department of Agriculture tried to develop a universal mosquito trap based on none other than … Limburger cheese.

This delicious gourmet food develops not only a traditional orange-red rind whilst maturing but also a strong and distinct odour. My colleague David Kline offered the cheese to 615 female mosquitoes from six different genuses: Aedes, Anopheles, Culex, Culiseta, Psorophora and Coquilettidia. The insects had the additional choice of clean air, human hands or socks worn for three consecutive days.

The result was quite surprising. Right from the start, the majority of flies preferred the socks (66.1 per cent) but hardly any showed interest in the Limburger (6.4 per cent). However, what was really intriguing was the insects’ persistent preference for the worn socks. Even after airing them for eight days, the mosquitoes still headed back for more.

This revelation somewhat defeats the popular summer camp strategy: “air your socks for a short time and put them on again”. Those of you with kids will know exactly what this means. In fact, they thus try to avoid one or the other visit to the notoriously disgusting toilet block on campsites and in youth hostels. Their only apparently “fresh” socks, however, would no doubt attract the insidious little hexapeds more than ever.

Kline‘s results at least have one faintly reassuring aspect: Although the fatty acids in Limburger cheese and those in the abrasions of unwashed human feet resemble each other quite closely, there is still sufficient variation in the composition of their other substances. The greedy female bloodsuckers, for example, are not so easily fooled by milk products and prefer to remain true to the evolutionary original – the sweating human.

IgNobel’s final assessment: despite the high potential for application and the admirable courage of the sock-wearers in the experiments, the paper didn’t qualify for an IgNobel award for reasons better known to the assessors. Well at least the Lab Times readers are now wiser and better prepared to make a stand against the whirring wings of future summers and tropical climates – provided they wear fresh socks!!

Mark Beneke

Photo: Pixabay/Fotovektor

Last Changes: 09.01.2017