Spider likes smell of dirty socks

Now there is another reason to put your dirty socks in the washing basket — their pungent smell could be attracting spiders.

But it is not the socks the spiders are after. Scientists have found some species of arachnid are drawn to human odour.

In a research laboratory in western Kenya, two New Zealand scientists, Fiona Cross and Robert Jackson, bred a group of adult and juvenile east African jumping spiders and exposed them to human scent using the smell of a worn sock.

When the sock odour was pumped into a series of chambers, the spiders spent significantly more time in the holding chamber than when the human odour was absent. A pair of white cotton socks were worn by an anonymous male for 12 hours before the trial.

Varying levels of carbon dioxide, heat, moisture and other compounds specific to human odour may alert the spider to the presence of a human, the researchers said. They believe the spiders were drawn to human odour because their main source of food is a group of mosquitoes, called Anopheles, that feed on human blood.

For both the spiders and the mosquitoes, detecting human odour appears to be an important step towards finding blood meals, said the researchers, from the School of Biological Sciences at the University of Canterbury.

For the spider, detecting human odour was probably more important for finding mosquitoes that are carrying the blood of recently fed-upon people than the people themselves, they said.