Jericho Conservation Newsletter #3
Earth Day
April 22, 2023
Soft, squishy, like a tootsie roll on legs. They are transformation specialists; transforming themselves and transforming energy from plants to other animals.
They have as many as 4,000 muscles, and 12 eyes (to differentiate between light and dark). They sometimes move their head from side to side. This most likely helps them judge depth and distance as they navigate somewhat blindly. They have way more than 6 legs, but most of those legs are false legs called prolegs, which help them hold onto plant surfaces and allow them to climb. The 3 pairs of legs on their thoracic segments are the true legs, which they will retain into adulthood. Welcome the mighty but often under-appreciated caterpillar.
The kid in me likes (native) caterpillars because they are easy to catch and observe up close for a long time. And they are like Clark Kent going into a phone booth and coming out as Superman - the caterpillar stops eating, hangs upside down from a twig or leaf, and spins itself a silky cocoon or molts into a shiny chrysalis. Within its protective casing, the caterpillar radically transforms its body, eventually emerging as a butterfly or moth. It even retains its memory through the transformation, though not the same brain.
Even before caterpillars become butterflies or moths (complete their metamorphosis), they change themselves many times. Consider this from the New Yorker article “The Little-Known World of Caterpillars” by Elizabeth Kolbert.
“Caterpillars, for their part, are continually reinventing themselves. They emerge from tiny, jewel-like eggs and for their first meal often eat their own egg cases. Once they reach a certain size, they sprout a second head, just behind the first. They then wriggle free of their old skin, the way a diver might wriggle out of a wetsuit. (In the process, the old head drops off.) In the course of their development, they will complete this exercise three, four, and in some species sixteen times, often trying out a new look along the way. The spicebush swallowtail, for example, which is found throughout the eastern U.S., emerges from its egg mottled in black and white. This color scheme allows it to pass itself off as a bird dropping. After its third molt, as a so-called fourth instar, it turns green (or brown), with two yellow-and-black spots on its head. The spots, which look uncannily like a pair of eyes, enable the swallowtail to pretend it’s a snake.”
The Marvels of Caterpillars: (as reported by Elizabeth Kolbert)
- The silver-spotted skipper uses an air-gun-like appendage in its anus to send its frass pellets soaring. This practice, known as “fecal firing,” discombobulates parasitic wasps.
- The silvery blue caterpillar possesses a “nectary organ” that dispenses a sugary liquid; ants attracted to the liquid are enlisted as bodyguards.
- The camouflaged looper confuses potential predators by chewing off bits of plant matter, like petals, and attaching them to its back.
- The catalpa sphinx caterpillar, when threatened, spews out green goo and thrashes around violently.
- The walnut sphinx caterpillar whistles through its air holes, or spiracles.
- The lace-capped caterpillar is colored to look like a piece of dying vegetation.
Why they are important:
We depend on the life support of functioning ecosystems.
By chewing and digesting leaves, caterpillars cycle nutrients and energy through the ecosystem, making valuable sources of nutrition available to other plants and living organisms.
Collectively, insects transfer more energy from plants to animals than any other group. They are the solder that holds food chains together. Ninety-six percent of our terrestrial birds rear their young on insects. Before they fledge, a clutch of young chickadees will consume as many as six thousand caterpillars. Think little sausages with a thin wrapper, soft and chewy, perfect for a mother bird to stuff down the hungry chick's mouth.
How are they doing?
There are indications that species losses are higher among species that prey on other insects. This may suggest that food webs were starting to break down.
Both species decline and mass declines of insects are being reported. Stressors include lights, pesticides, habitat loss, climate change, pollution, exotic species, and the industrialization of agriculture.
Two years ago the UN said one million species face extinction in the next 20 years. Many flowering plants are so closely linked to butterflies (and vice versa) that one cannot survive without the other. Monarchs have declined 85% in two decades.
What can we do to help?
As Doug Tallamy, entomologist and author says, we need a new approach to conservation. The ability to do so is on us, the location is in our yards. We need to change the way we landscape to save nature, to save ourselves. We need a land ethic where we live with nature. Much of conservation depends on the accumulation of small-scale advances.
Yes, we need flowering plants to turn the sun into food (along with the ever-important pollinators). We also need insects that turn plants into food that other animals can eat. Caterpillars transfer more energy from plants to other animals than any other plant eater. They are one of The World’s Greatest Super Heroes. Not only do they go into their own phone booth and come out totally transformed, but they also become beneficial pollinators as well as sources of food for birds, predatory insects, and other animals. Caterpillars can be the foundation of the biodiversity of our gardens and landscapes.
Caterpillar diversity is near if not equal to the diversity and beauty of butterflies and moths. Whether watching a caterpillar eat a milkweed, finding a chrysalis hanging from a leaf, or following a Monarch floating in the wind, we can imagine we have the superpowers to find and express our identity in a complex and ever-changing world. And we can realize like us, not every caterpillar species is the same, each has its own special powers, its own unique look, and its own way of making its way in the world; each contributing to a biological diversity that supports all life on earth.
Together we can protect this species; as a community of people who care about wildlife, there are actions we can take to help.
Most of our birds nest a short distance from where they find food to feed their young. Want birds to breed in your yard? Consider shrinking lawn space. Put the native plants back. Feed the caterpillars to feed the birds and other animals.
Let's say "Yes in my backyard
- to Nature and Rewilding".
I have observed in our 1.3-acre yard and recorded on iNaturalist, 197 species of Lepidoptera (Lepidoptera is the order of insects that butterflies and moths are assigned) 115 species of butterflies.
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| Virginia Ctenucha Moth Ctenucha virginica |
However, the caterpillars must have access to the right kind of food and habitat. View a list of Vermont plants that will support caterpillars and how many species of caterpillars each plant genus will support at https://vtbugeyed.blogspot.com/2023/03/vt-native-trees-and-shrubs-as-moth-and.html. These are plants that contribute to the (Vermont) local food web. Most of the insects that eat plants are host-plant specialists, they can only eat particular plants. That is why we focus on a diverse mix of native plants that support insects, especially those soft squishy tootsie rolls on legs. Bon Appétit ma/mon chenille!
The shortest path to a beautiful butterfly or moth is to follow a caterpillar.
Photos below are from observations at Kikas Valley Farms Trail, Jericho, Vermont on March 20, 2023. Both caterpillars were on the snow about 300 feet from any trees.
References
The Little-Known World of Caterpillars (The New Yorker article)
***Nature's Best Hope with Doug Tallamy (VLT video recording)
Rare, Declining, and poorly known Butterflies and Moths of Forests & Woodlands in the Eastern U.S.
VT Native Trees and Shrubs as moth and butterfly hosts (Plant list)
10 Fascinating Facts About Caterpillars
Moth decline in the Northeastern United States
- A note on invasive caterpillars like the Spongy Moth introduced to the United States from Europe during the 19th century. Many of its important natural enemies were left behind in its native lands when the gypsy moth became established here. However, there are some natural enemies of spongy moths - some, birds, mammals, parasitoids, and pathogens - in Vermont.
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