If you’re a froghopper you needn’t worry about having ‘spikey’ legs, as it turns out the spines help to pierce into leaves which in turn prevents slipping when jumping from smooth surfaces.
Froghopper Factfile:
Froghoppers are 5-7mm long, come in many different colourations (called colour morphs), are very common and can be seen in the UK between June and September. You may be familiar with the larvae-produced bubbles that appear on vegetation in spring and summer. Known commonly as ‘cuckoo-spit’ – although nothing to do with cuckoos. The frothy mass is actually where their nymphs reside for protection.
Also known as Spittlebugs, or Philaenus spumarius for the more scientifically inclined of you, the common froghopper holds the current world record for height of jump in the insect world.
Scientists from the University of Cambridge originally recorded froghoppers jumping to a height of 27 inches (~70cm), which is the equivalent to a man jumping over a 690 ft skyscraper!
Jumping at an acceleration of 13,000 feet per second, the froghoppers overtook fleas to the title of worlds best insect jumper. Their hind legs are so powerful that a G-force of over 400 gravities is generated in the early stages of their jump. To put that into perspective, an astronaut rocketing into space experiences a G-force 5 times greater than gravity, and a jumping human experiences a force of about 2 times greater.
Now, the scientists have made a new discovery.
Keep reading to find out what they have found!
Spiny legs prevent slippage
A study by Goetzke, H.H., et al. (2019) from the University of Cambridge have found that froghoppers produce traction when accelerating for jumps by piercing plant surfaces with sharp metal-enriched spines on their hind legs. They even saw the microscopic holes left by the spines on the leaf surfaces.
The scientists wondered if froghoppers are able to take off from smooth surfaces. When jumping from a glass surface, the insects were unable to pierce the substrate, and so their hind legs slipped and they performed much weaker and uncontrolled jumps. When jumping from ivy leaves that had smooth epoxy surfaces, the froghoppers jumping performance contrasted greatly – being strong and without slippage.
This is due to tiny spines on their tibia and tarsus that they use to pierce into the substrate of which they’re jumping from, allowing them to grip.
The discovery of piercing as a new ‘attachment strategy’ may represent a method of moving that may be widespread amongst other plant-living insect species. Yet not previously recognised. Furthermore, it could be an inspiration for future robotic engineering, such as when developing grabbing mechanisms or climbers.
Reference used:
Goetzke, H.H., Pattrick, J.G. and Federle, W., 2019. Froghoppers jump from smooth plant surfaces by piercing them with sharp spines. Proceedings of the National Academy of Sciences, 116(8), pp.3012-3017.
