CLEVER CATERPILLARS

Butterflies, like all organisms, are intent on surviving. Some live for only a few days while others live for many months in their adult stage, often surviving harsh winters or perilous journeys to food and breeding grounds. The goal is always the same: to mate, reproduce and continue the survival of the species.

Some butterflies have evolved clever tactics to disguise themselves and avoid predation by birds. The viceroy butterfly has wing venation and color that resembles those of the monarch butterfly, a species that is toxic to birds. Monarch caterpillars ingest chemicals from milkweed plants (Asclepias spp.)  that make the adult butterfly particularly unpalatable and in some cases, toxic. Birds know this. By assuming the color and pattern of the monarch, the viceroy evades predators.  Similarly, the red spotted purple exhibits mimicry as it has evolved to look a lot like the pipevine swallowtail, which is also toxic or unpleasant tasting.  Birds don't take a chance and stay clear of the red-spotted purple, which, I bet is is absolutely delicious.

                                                                                                                                                                                        The orange dog (which is the caterpillar of the giant swallowtail) looks like bird poop. Spicebush swallowtail caterpillars have fake eye markings  that make them look like a snake, a clever strategy to confuse and  intimidate bird predators. 

The relationship between the nymph stage of the ladybug and the swallowtail caterpillar is a source of wonder to me. They both thrive on fennel (Foeniculum vulgare) in my garden. The tiny caterpillars eat the leaves while the ladybug nymphs eat the aphids that suck juices from the plant. Paper wasps prey on swallowtail caterpillars. Great for the plant but not so for the black swallowtail, which is one of my favorite butterfly species. 

 

 

 

Once the plant, with the juicy soft bodies is discovered, wasps hang around for a feast. What is remarkable is the resemblance between the young caterpillars and the ladybug nymphs. I often wonder if the caterpillars have evolved to be mistaken for nymphs. Tricky!  

 

 

 

 

 

Newly hatched black swallowtail caterpillars have a white bar around their midsection and stubby projections overall.

 

 

 

 

 

As they grow older, the black swallowtail caterpillars look nothing like when they are newly hatched.  Their color changes to a stripped white, black and yellow to greenish coat.

 

 

Nevertheless, they are still preyed upon by wasps. I know they must eat too but I am bias and would much rather  have more caterpillars than wasps on my fennel plant. I also welcome the ravenous ladybug nymph. Without it I think there would be many less black swallowtails for us to enjoy.