Monday, April 6, 2015

Snake Head Caterpillars

A couple days ago I was examining the leaves on our potted tangerine tree and noticed a lot of black specks on the cream colored patio surface. Hmmm...looked like frass to me (the scientific word for caterpillar poop!). I looked above the droppings for evidence of caterpillar(s) and found this interesting larvae! On first glance, it looked like the head of one of those tiny tree vipers in Costa Rica. 

I did some Googling and found out that there are several species of snake like headed caterpillars- an amazing morphological adaptation that evolved to protect them from predators. Some even mimic the striking behavior of snakes. This one turned out to be the larva of the Giant Swallowtail (Papilio cresphontes), the largest butterfly in North America that is quite common in Florida. It must have laid its eggs on the leaves while the tree was outside during our lanai restoration. They are considered a pest in citrus orchards. 

The larvae mimic bird droppings, an example of biological mimicry. The later instars' thorax begins to resemble a snake's head and will adopt a striking pose so the one I found was an older larva, soon to chrysalize. Upon further examining the tree I found one more larva. I took these photos with a regular lens- wish I had used Chris's macro lens to capture the detail. Oh well, I guess this is an excuse to buy myself a macro lens for closeups as I am sure I will find many more interesting species of insects here in SW Florida!

Afternote: I found 2 more late instar stage larvae on the tangerine tree today. Decided to keep them, hoping they will chrysalize and I will have two giant swallowtails fluttering inside my screened lanai!



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