Desert locust. Macrophotograph of the discarded skin (molt) of a desert locust, Schistocerca gregaria, after metamorphosis. Metamorphosis is the name given to a bodily change. As locust larvae (nymphs) mature, their external skeleton cannot increase in size to accomodate the growing body. The larvae therefore grow a soft skin before breaking out of their old skin & leaving it behind. The new skin is then quickly expanded before it hardens due to contact with air. Locust larvae undergo several such moults, increasing their size from about 8 millimetres to 3 centimetres. They then undergo a final moult into the adult form.