Poison as protection

Heliconid caterpillars can eat these leaves safely. In fact, for them, the poison is an advantage: it stays in the caterpillars, making them poisonous...so birds that would otherwise eat them leave them alone.

And when these Heliconid caterpillars grow up and turn into butterflies, the chemicals still remain. Heliconid butterflies too are poisonous.

Sometimes, passion flower vines start producing a new poison that works even on Heliconids...but in a while, news types of Heliconids develop that are immune to the news poison. The struggle for survival between plants and plant-eaters goes on and on.


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