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This is the SAME individual katydid from just after hatching to adult.
As a first instar nymph (fresh out of the egg) the little katydid behaves much as an ant or a wasp. The antennae flicker when it moves in a wasp-like fashion and its movements are jerky.
After a few moults the same katydid looks quite different. Note the difference in colour pattern and also the antennal colour is entirely black and does not have the white patch near the base of the antenna as is seen on the first instar.
So are there explanations for this scenario. It's diverse changes are not just happenstance in my opinion. The wasp-like or ant-like appearance and behaviour of the first instar may help it avoid being predated upon by lizards and birds when it is on the ground or on tree trunks. The mid instar appearance might be protective in the sense that it appears more like a piece of bark or leaf litter than an edible katydid. At this stage its movements are jerky and wasp-like. Later instars are probably on leaves during the day and the green colours and patterns conceal it. The adult is not unlike any of the more than 10 species of the Phaneropterinae that occur with it. The katydids are nocturnal and spend their time in foliage. They are vegetarians.