

Video: Cockroach slipping off coated glass rod Video: Cockroach slipping off coated glass rod

Sticky fly traps? So twentieth century, darling. Scientists have identified a cheap, durable and eco-friendly chemical that, when painted onto walls, baby bottles and crops, gets rid of pests by making their feet “sweat”.

Insects normally have no trouble strolling up walls and across slippery surfaces. Tiny pads on their feet secrete a ketchup-like glue – part oil, part water – that holds them in place.

Now, Jan-Henning Dirks and colleagues at the Department of Zoology at the University of Cambridge say they have found a way to turn this glue into a slippery lubricant.

Dirks’ team painted glass rods with a range of chemicals and compared how these affected the ability of cockroaches to climb up the rods to a piece of apple. They also measured the frictional force between the roach’s feet and the surface of the rod.


Greasy insect

They found that roaches effortlessly shimmied up rods coated in PTFE, a non-stick coating commonly found on cooking pans. But when the rods were covered in polyimide resin, the creatures lost their grip. In fact, the resin reduced the friction between the insects’ feet and the glass rods by around 60 per cent. “The cockroaches simply slid off the rod,” Dirks says.

Using interference reflection microscopy, the scientists discovered that polyimide resin sucks up the water contained in the insect’s glue – leaving behind a slippery layer of oil with no adhesive properties.

“In the future, this could prove to be a powerful tool to prevent pests from scuttling around on many hard-to-reach surfaces,” says Dirks. Because the water absorbed by the resin evaporates quickly, the resin never needs to be replaced. “As a result, it’s far cheaper and more eco-friendly than conventional pest-controlling methods.”

Whether the technology will control flies, earwigs and geckoes, which use a slightly different form of “glue”, remains to be seen, says Dirks. Any possible side-effects of the resin on wildlife will also need to be investigated.