Frangipani Caterpillar Mystery

St. John Fauna: Frangipani Caterpillar
Frangipani Caterpillar

I’m at a loss to explain the relationship between the farngipani caterpillar and this particular native frangipani tree I have growing right beneath my deck.

Normally the tree blooms, producing new leaves and flowers. At this point the frangipani caterpillar hatches from eggs laid on the underside of the leaves and then proceeds to eat all the leaves and flowers. Their excrement fertilizes the tree and the cycle continues.

On this tree, however, the caterpillars emerge as soon as the tree starts to sprout new leaves. The sprouts are devoured and the leaves and flowers never emerge. (I provided the above photo for those who doubt me.) I have been here about ten years and I’ve only seen the tree flower once. Apparently the symbiotic relationship is still working. I estimate the tree to be at least 70 years old, evidenced by a rusted piece of wire fencing that had grown into the trunk and now sticks out on both sides of the tree, indicating that this was a mature tree when Chocolate Hole was still used for grazing animals. The abnormal relationship with the caterpillar hasn’t killed it yet, but I’m at a loss to understand how. For instance, if the caterpillar lays it’s eggs on the underside of the leaves, and there are no leaves allowed to grow, where do the new caterpillars come from? And how does the tree photosynthesize without leaves?

At any rate, I’ll be studying this tree further and taking more photos which I’ll share.

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One thought on “Frangipani Caterpillar Mystery”

  1. Hi, I just returned from St. John (my wife and I love to vacation there). I study spiders, and while on a hunt happened upon this beautiful and fascinating caterpillar and filmed it. I spoke with a few park rangers while there and they informed me that this caterpiller feeds on the leaves and sap of the Frangipani tree, which are poisoness. There brightly ornate bodies (like several vulnerable critters) warn off preditors, such as birds that this caterpiller, “could be hazardous to your health; best to avoid me!” Apparently though, it has no effect on the Frangipani caterpiller. I will be up-loading a video of my nature walk in St. John to YouTube in a few days. I have lots of videos on YT on a channel called, “Bob The Spider Hunter.” You might like to check it out! Take care,

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