Mid to late summer and early autumn is a great time to appreciate caterpillars. Many people view them as creepy crawlies to be eliminated by the speedy application of a size 13 shoe, but, wait! The gorgeous monarch butterfly comes from a lowly caterpillar as does the impressively large luna moth.
Caterpillars can be small or large, flamboyant or plain, smooth or spiky, but they all transform into a moth or butterfly. Butterflies and moths belong to the insect order Lepidoptera, from the Greek words lepis, meaning scale, and pteron meaning wing. For a couple of days last week, my timing was perfect and I was able to watch a monarch caterpillar feeding on my butterflyweed blossoms. One of my coworkers identified a viceroy caterpillar on the limb of her fruit tree, an impressive find since the caterpillar resembles a bird dropping and so is easily overlooked! Caterpillars, which are the larvae of Lepidoptera, are themselves fascinating and seeing how beautiful they are as adults makes them even more extraordinary.
If you remember back to high school science, Lepidoptera develop by complete metamorphosis in four distinct stages. Adults lay eggs which then hatch into caterpillars, the larval stage. The newly hatched larva is also called an instar. As the it grows and matures, it sheds its skin, or molts, but is still considered an instar. Some species go through many instars before reaching maturity. For example, a monarch goes through five instars, growing from the first instar at roughly 0.078 to 0.24 inches long to its fifth instar at 1.0 to 1.77 inches long. The fifth instar weighs approximately 2,000 times more than it did as a first instar! For butterflies, the last instar then pupates and forms a chrysalis. For most moths, the last instar forms a cocoon but some spend this stage in protected chambers in soil or wood. The length of time the pupa spends in this stage varies from species to species, until it emerges at last as an adult butterfly or moth.
Lately, there has been a significant move to understand and share the importance of pollinators. Many Lepidoptera (along with bees, wasps, birds, flies, and beetles) help flowering plants and food crops reproduce. It is estimated that one out of every three bites of our food, including fruits, vegetables, chocolate, coffee, nuts, and spices is created with the help of pollinators. While caterpillars are not pollinators, we need caterpillars to grow up to be butterflies and moths to help produce our food.
Caterpillars are important to the web of life in another way. They support our wildlife. Doug Tallamy, professor in the Department of Entomology and Wildlife Ecology, University of Delaware, has studied caterpillars extensively. Ninety six percent of our terrestrial birds raise their young on insects, particularly caterpillars. Baby birds cannot eat seeds so their parents switch to mostly caterpillars for several reasons:
• They are soft and easily pushed down the throats of the babies, unlike an insect like a beetle, much of which is undigestible and has sharp edges.
• Caterpillars can be large so one caterpillar goes along way to providing high fat and protein to the baby. It is easier to find one caterpillar than the nutritional equivalent in aphids which would mean finding 200 aphids.
• Caterpillars are high in carotenoids, which are essential to vertebrates. Since vertebrates cannot make their own carotenoids, they get them from plants. The caterpillar eats the plants that provide the carotenoids that the birds need.
Extensive research on the Carolina chickadee by Richard Brewer (professor emeritus, Department of Biological Sciences, Western Michigan University), detailed the role of caterpillars. Parent chickadees typically find food for their babies within 50 meters of the nest. The babies are fed for 14 days in the nest, and then the parents feed them another 21 days as fledglings. This means the parents locate and bring back 390 to 570 caterpillars every day to the nest for a grand total of 6,240 to 9,120 caterpillars to raise one clutch! An adult chickadee weighs only one third of an ounce so imagine how many caterpillars a larger bird such as a red bellied woodpecker would have to bring back to its nest!
The Ohio Division of Wildlife has free downloadable color field guides on butterflies and moths, with photographs of the caterpillars included at https://ohiodnr.gov/wps/portal/gov/odnr/discover-and-learn/safety-conservation/about-odnr/wildlife/documents-publications/backyard-wildlife-documents. You can also view presentations by Dr. Doug Tallamy at https://u.osu.edu/certify/living-landscape-speaker-series/.
To learn how to host a diverse array of captivating caterpillars, visit www.nwf.org/nativeplantfinder. You can view a colorful variety of pollinator friendly plants at the Delaware Soil and Water Conservation District’s natural resource area at the Delaware County Fairgrounds, located next to the pig and lamb barn.
Bonnie Dailey is deputy director of the Delaware Soil & Water Conservation District. For information, go to https://soilandwater.co.delaware.oh.us/.