“Caterpillars are really just walking leaves, for that is all they eat.”
–Douglas W. Tallamy, The Nature of Oaks
I am reminded of this sentence in Tallamy’s latest book every time I encounter a caterpillar in my yard. It feels to me to be a deep and important truth, one that is easily overlooked by many, I fear.
He notes in another paragraph that he wants people to stop thinking of caterpillars and other insects as bugs. Instead, he asks us to remember that every stink bug, caterpillar, wasp, and ant is potential food for an animal, perhaps another insect or spider, perhaps a bird, perhaps a mammal. Wildlife needs those bugs to keep the cycle of life operational.
Now, instead of caterpillars, I see leaves with legs. And although, Tallamy didn’t write it, I now see the butterflies and moths that these caterpillars become as leaves that fly — farther than an autumnal tumble from branch to earth on a chilly north wind. Flying lepidopterans allow leaves, albeit transformed ones, to travel much farther. I am hoping that some of the transformed leaves of swamp milkweed in my garden make it all the way to Central America in the form of a Monarch butterfly migrational journey.
It has been a tough year for the leaves-with-legs in my yard. Predatory wasps and birds got most of the early rounds of Monarch butterfly caterpillars that appeared on my common and swamp milkweeds. One moment, the tiny hatchlings would be happily chomping away. The next — nothing, save a few bits of frass (caterpillar poop) adorning leaves below those on which they were feeding.
Two weeks ago, I was elated when I spotted eleven small Monarch caterpillars dining on swamp milkweed near my front water feature. Wasps were no longer patrolling the plants, their life cycles completed for the season. I thought these leggy leaves had a real chance to make it to their next transformation. For nine days, they grew fatter. I felt certain they were close to their time to become bejeweled emerald chrysalises.
One by one, they began to vanish. Caterpillars wander when they are preparing to pupate. They deliberately leave their food plants and search for another place to build their magic metamorphic enclosures. I searched carefully all around for signs, seeking walking leaves dangling from stems of other nearby plants in the classic J position they assume before they melt into the gilded jewel boxes from which they emerge as winged leaves ready to fly south.
Finally one afternoon, I spotted a fat caterpillar walking on the ground around the water feature. I feel certain it was seeking a plant upon which it would metamorphose. Just as I excitedly pointed out this caterpillar on its transformational journey to Wonder Spouse, one of the Green Frogs spending the summer in our water feature jumped down from the rim of the pool, and before we could blink, we watched the amphibian grab the caterpillar, swallowing it in two big gulps. We were stunned. And horrified.
Of course, I know that frogs eat insects, but it never occurred to me that they would eat caterpillars as they descended the milkweeds to metamorphose. Later that day, I spotted perhaps the same frog staked out beneath a milkweed that still had two caterpillars dining on it. It was very clearly waiting for them to descend and become its next meal. I confess, I chased the frog back into the water feature, scolding it.
After scouring the area for signs of transforming Monarch caterpillars, I found only one dangling from a spent scape of a daylily. It was in the J position that afternoon, safely beyond the reach of greedy frogs. By the next morning, the leaf with legs had become a jade green chrysalis. I have moved it to what I hope is the safety of my greenhouse before predicted rains could potentially enhance opportunities for fungal contamination or predatory wasps/flies could harm it.
I visit it several times a day to encourage it on its metamorphic journey. October seems to be planning to stay warmer than “normal,” but one never knows when a cold front might blow in with the first frost. It’s not unusual for Monarchs to migrate in late October, so there’s every reason to hope for a positive outcome for this little emerald jewel box.
Still, my heart will lighten when metamorphic magic transforms the chrysalis into a leaf with wings that will carry it safely to warmer winter climes.