Grasshopper

They are in the same order, Orthoptera, but different suborders. Grasshoppers have short antennae, usually shorter than the body, hold their wings tented over the back, are active by day, and make sound by scraping the hind leg against the wing. Crickets and katydids have long, thread-like antennae often much longer than the body, are mostly active at night, and produce sound by rubbing the two forewings together. Crickets also have a long needle-like egg-laying tube on the female and hearing organs on the front legs rather than the abdomen. In short, a slim green or brown day-active jumper with short antennae is a grasshopper; a long-antennaed night singer is a cricket or katydid.

A typical grasshopper can jump about twenty times its own body length and roughly ten times its height in a standing leap, and it can do this repeatedly without tiring. The power comes from a catapult mechanism rather than raw muscle. Muscles slowly contract to bend the large hind-leg joint, energy is stored by deforming a springy pad of cuticle and a curved structure called the semi-lunar process, a catch holds the joint cocked, and then the catch releases and the stored energy is dumped in a couple of thousandths of a second, far faster than muscle alone could move. Many grasshoppers also open their wings at the top of the jump and glide onward.

Only certain species can do it, and only under the right conditions. In these species, called locusts, the insects exist in two forms. In the solitary phase they are shy, cryptically coloured, and avoid one another. When a run of good weather produces a population boom and then dry conditions concentrate the survivors onto shrinking patches of green, the crowding itself, sensed partly through repeated contact on the hind legs, triggers a change over one or two generations into the gregarious phase, which is brighter, more active, and strongly attracted to other locusts. These gather into bands as nymphs and into swarms as adults, and can travel long distances stripping vegetation. The desert locust is the most infamous example.

Most grasshoppers cause little damage, but in warm, dry regions some species build up in large numbers on rangeland and field margins and move into crops, chewing leaves, stems, and grain heads. Serious outbreaks, especially of locusts in Africa, the Middle East, and Australia, can destroy pasture and harvests over wide areas and are managed by governments with monitoring and targeted spraying. In a garden, grasshopper damage is usually patchy and seasonal, worst in a hot dry summer, and can be reduced by encouraging birds and other predators, keeping some rough grassy areas away from beds, and covering vulnerable plants during a local surge.