There is a battle going on out there that most are not aware. It’s the ongoing war between the heliconius butterfly and the passionflower vine.
Though the leaves of the passionflower are poisonous to larvae, the caterpillars of the heliconius butterfly thrive on them with no ill-effect. Hence these brightly coloured insects make it a point of laying their eggs on these particular plants, – it’s great to have no completion, or so it seemed.
In self-defence, the passionflower vine has adapted, enabling them to vary the shapes of their leaves to resemble other plants to fool the butterflies which primarily rely on sight. To counter these, some of the butterflies took up drumming. They drum their legs on the leaves and the vibrations let them know if they are parked on the passionflower.
The vines’ Plan B was to produce fake eggs in the form of yellow spots. The butterflies tended to avoid these.
Some of these vines developed poisonous spikes to combat the caterpillars while others drop tendrils soon after forming. Any eggs there would fall with it and not survive. If that was not enough, the nectar produced by the flowers attracts ants and wasps that would prey on any caterpillar about.
The battle still continues but with a little irony. The toxins from the passionflower’s leaves are absorbed by the butterflies making them unpalatable to birds. They now live longer than many other butterfly species and will undoubtedly develop new weapons of war.