For two summers, our region of the Catskill Mountains, in upstate New York, was hit hard by forest tent caterpillars, whose effects cascaded through the food chain.
This caterpillar, a native species known since colonial times, periodically peaks in numbers, defoliating sections of the mountainside as part of natural selection, weakening and pruning out the less hardy trees. Although not directly fatal to trees, the caterpillars destroy enough leaves to force many trees to put out a second set of leaves in midsummer, using up stored resources.
The loss of leaves means that sunlight reaches the ground in early summer, when sunlight-loving seeds ordinarily would not germinate in the woods. As a result, knee-high jewelweed and white snakeroot carpeted our forests those two summers.
While the loss of leaves and invasion of fuzzy creatures was distressing to the local humans, one unexpected benefit was the jewelweed’s attractiveness to pollinators. Its bright yellow or orange flowers store nectar deep in the spur end of the blossom. Large bees and hummingbirds are drawn to the flowers.
Although no one did a scientific study of the hummingbird population in the region, I can say anecdotally that I had never seen so many ruby-throated hummingbirds as I did those two summers, and I suspect that the explosion of jewelweed had something to do with it.
Aside from providing us humans with some recompense for the damage to the trees, the jewelweed-hummingbird effect offered a lesson in the interconnectedness of the elements of nature, often in ways we do not notice. It makes me shudder to think of how people are conducting genetic manipulation of plants, without the ability to understand its long-term effects.
