Dutchman's Pipe and Pipevine Swallowtail
Many of the
plants outlined in this chapter are most visible in the spring, but you
will notice the interwoven vines of Dutchman’s Pipe at any season of
the year. Like the wild grapes that grow nearby, Dutchman’s Pipe
begins as a sprouted seed on the forest floor, then winds its way up
into the canopy, draping over tree branches to cushion its
ascent. Unlike the grapevines, though, Dutchman’s Pipe has
smoother bark that does not come loose in curling strands.
If you keep
your eyes open in June, you may see another field mark of the
Dutchman’s Pipe --- black caterpillars speckled with orange
spots. These are the offspring of the Pipevine Swallowtail, so
named because its caterpillars munch solely on the leaves of Dutchman’s
Pipe and the related Pipevine. You have probably heard of Monarch
caterpillars that will only eat milkweed and related plants, but you
may not realize that several other caterpillars are just as picky
eaters. Adult butterflies, like many adult humans, are happy to
flit from food source to food source, but caterpillars are more like
human children who refuse to eat anything except pizza. To the
caterpillars of the Pipevine Swallowtail, Dutchman’s Pipe is pizza ---
the only food worth eating.
Why so
picky? Scientists cannot explain why your kid will only eat
pizza, but they have made progress toward deciphering the picky nature
of Pipevine Swallowtail offspring. As the caterpillars munch on
Dutchman’s Pipe leaves, they gather poisons out of the plants and
safely pack them away within the caterpillars’ own bodies. Blue
Jays and other predators may consider the big caterpillars and
butterflies easy pickings, but as soon as they eat their first poisoned
caterpillar, the jays get a serious case of food poisoning and quickly
learn to hunt down more nutritious food. Although a few Pipevine
Swallowtails may die in the process, the species as a whole is able to
bypass most predators through its childhood of picky eating.
As you will
soon learn, nature is full of cheats. Several other butterflies
in our area look remarkably similar to Pipevine Swallowtails --- the
most common example is the black female version of the usually yellow
Eastern Tiger Swallowtail. The Eastern Tiger Swallowtail
caterpillars cannot eat Dutchman’s Pipe leaves without getting sick
themselves, but they can mimic the species that does. The
result? Blue Jays tend to leave the black Eastern Tiger
Swallowtails alone, afraid to take any chances on another noxious
nibble. Like the grapevine, the Eastern Tiger Swallowtail has
learned to get ahead by working the system.
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