Cambridge scientists getting to grips with what makes stick insects stick.

It's long been a matter of some conjecture - how the stick insect is able to stick. Well, scientists in Cambridge may have discovered the reason.

They've found that geckos, tree frogs, spiders and insects all share a special skill – they can walk up vertical surfaces and even upside down using adhesive pads on their feet.

But geckos have ‘dry’ feet, while insects have ‘wet’ feet. Scientists have assumed that the two groups use different mechanisms to keep their feet firmly attached to a surface, but new research from David Labonte and Dr Walter Federle in the University of Cambridge’s Department of Zoology provides evidence that this isn’t actually the case.

“It has generally been assumed that the fluid on their feet must be involved in helping insects like stick insects adhere to a surface by capillary and viscous forces – in the same way that a beer glass will stick to a glass table if it’s wet on the bottom.

"Our research shows that the fluid is likely used for something else entirely – it may even help insects unstick their feet.”

– DAVID LABONE, REPORT AUTHOR

By measuring how much force was required to detach the foot of a stick insect from a glass plate at different speeds and applying the theory of fracture mechanics, Labonte and Federle found that only a ‘dry’ contact model could explain the data.

Read on ...