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Leafhoppers

Posted: Tuesday 19 November 2013
by Richard Jones

I have a world-record holder in my garden. The best jumper in the animal kingdom lives in my ivy hedge.


I have a world-record holder in my garden. The best jumper in the animal kingdom lives in my ivy hedge. Forget kangaroos and grasshoppers, even fleas, I have Issus coleoptratus basking on the leaves in the slanting November sunshine.
 
It’s a shame there is no common English name for this handsome insect, so ‘leafhopper’ or ‘froghopper’ will have to do, even though those names cover several hundred different UK species. Anyway, it can’t half hop.
 
Although only 3-5 mm long, it’s a distinctive beast - similar size and muted brown colours to the common spittle bug froghopper, Philaenus spumarius, but a lot blunter, broader and chunkier. This broadness across the shoulders is the secret of its Olympic jumping ability. Here’s a short biology lesson...
 
Froghopper jumping is not just by contraction of leg muscles propelling the body into the air. Instead, elastic energy is stored, then suddenly released. Huge muscles bend a bow-shaped arch of chitin (the hard but flexible material insect shells are made of), and a rubber-like protein called resilin inside the insect’s thorax. At a critical point the tension is released, like an arrow being set off from a bow, propelling the legs down, and the insect upwards.
 
Issus is also unique (apparently) in having interlocking cogs attached to the bases of its legs so that they push at exactly the same time and speed, otherwise it would go off sideways, spinning wildly out of control.
 
The leap happens in milliseconds, and the numbers are staggering. Issus can leap 100 times its own body length, has a take off velocity of 5.5 m/sec (19.8 kph, 11 mph) and within a thousandth of a second achieves an acceleration force equivalent to 719 gravities.
 
This is all happening in my hedge. Astonishing.



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