Bald Head Island Conservancy

Field Guide: Flutterbys from the Front Porch

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by Morgan Hooks, Environmental Content Creator

In North Carolina, there are an estimated 2,000 to 2,500 species of moth, soaring over the 174 observed species of butterfly in the state, according to North Carolina Parks. Of these, 99 are classified as species of concern by the North Carolina Heritage Program; primarily those in the mountains, sandhills, and here on the coast. The diverse landscapes of Bald Head Island, consisting of the maritime forest, dunes, and salt marsh, provide refuge for a range of insects including migratory moths. In turn, the moths provide pollination for our native plants and eventual food sources for many of our neighboring frogs, fish, and birds.

May welcomed these migratory moths to the island, found fluttering through the bushes or resting their wings on the Conservancy campus porch, with a colorful selection of caterpillars crawling across the wooden stairs soon after. Sitting outside on our campus each afternoon inspired my curiosity about the moths and their caterpillars, particularly how their process of chrysalis and metamorphosis occurs. Most of the moths that I observed have a spring to early-summer seasonality on Bald Head Island, but a few can also be seen further into the fall. These moths may be using the island to reproduce, metamorphosize, or rest their wings mid-migration. Our porch offered a front-row seat to observe the next generation emerge with the spring.

At the beginning of May, I observed several species of adult moths either amongst the tree canopy on our campus or resting along the window panes or our deck chairs. I used the iNaturalist app to document the moths that I observed and to research their taxonomy, seasonality, range, and distinctions. I initially noticed the Polyphemus Moth (Antheraea polyphemus), a member of the Silk Moth family. As a name, Polyphemus is derived from the Greek myth of the Cyclops Polyphemus, whom these moths are akin to because of the eyespots seen on their hind wings. I identified both a male and female Polyphemus Moth, both at rest.

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You can distinguish male (left) from female (right) from the size of their antennae, with the male’s being big and bushy compared to the female’s thin ones.

I next identified an Agreeable Tiger Moth (Spilosoma congrua) camouflaged against the white stairs. One of three species in the White Tiger Moth family, these moths are similar to their cousin the Virginia Tiger Moth, both noticeable for their fluff of fur surrounding their head, white speckled abdomen, and their tented wings when at rest.

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Unlike their cousin, Agreeable Tiger Moths possess a “bib” of orange, which you can see partially peek through the white fur in my identification photograph.

As we approached mid-May, I began to observe one-to-five caterpillars at a time on our campus, often crawling across the steps of our porch or the posts of the awning. I observed two species of Tussock Moth caterpillars, characterized by their tufts of irritant hairs. During their larval state, these moths range from 1-1.5 inches. Tussock Moths also possess noticeable verrucae, or wart-like structures, along the mid-section of their bodies, which vary in color.

I first observed a Fir Tussock Moth (Orgyia detrita) caterpillar, which can have both a dark, gray form or a light, pale yellow form. Both forms showcase a gray-toned verrucae.

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Another distinguishing characteristic of Tussock Moths is the antennae (composed of black hair-like setae) on both their head and backside. 

I observed only one Definite Tussock Moth (Orgyia definita), which I followed on its travels from the front of Barrier Island Study Center to behind Turtle Central. Definite Tussock Moth caterpillars are a pale yellow similar to the Fir, but rather possess vibrant yellow verrucae.

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Adult male Definite Tussock Moths display an approximately 30 mm wingspan, whereas the adult female moths are wingless.

Lastly, I observed an Arge Moth caterpillar (Apantesis arge), which I initially mistook for a Wooly Bear Moth. While the Arge Moth has a similar wooliness throughout, its yellow and black striping is what distinguished it as an Arge Moth, a member of the Erebid family.

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Arge Moths migrate from as far north as Quebec to as south as Florida and are on-wing throughout most of the summer and into early-fall.

By the end of May, caterpillars made their way to the porch awning, beginning to cocoon and complete chrysalis. Although I did not see which species cocooned themselves, the silk-ish appearance of the cocoons favor those of Tussock Moths, along with the chosen location, as Tussock Moth cocoons are often spotted under the soffits of buildings. Moths can cocoon from a window of five to twenty-one days, and around the tail-end of the window in early-June, I noticed that the cocoons had hatched.

I did not observe adult counterparts of any of the species I previously observed, however, I did discover a new species in the same week that the cocoons hatched, whether the moth was a recent hatchling or a passerby. Nestled into the screen of one of our lab windows was a Large Maple Spanworm Moth (Prochoerodes lineola).

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Both larval and adult Large Maple Spanworm Moths are able to camouflage from bats and birds, the caterpillar disguised as a twig and the moths as a leaf.

We are fortunate that these moths chose our campus to carry out the creation of the next generation of moths and, in turn, that we were able to witness the three different stages of their lives, from reproduction, to the larval stage of the caterpillars, to this new generation emerging from their cocoons and soaring into the skies.

Moths are often stereotyped as the lesser butterfly, however, moths are important members of each of our four distinct ecosystems on Bald Head Island and the health and functionality of them. It is a magical thing to be given the opportunity to sit back and study a species as it carries out the metamorphosis of its life, along with how it interacts with and impacts its neighbors, both friend and foe.

For those interested in spreading their wings and discovering the study of insects, entomology, visit inaturalist.org. Budding bug-watchers can also participate in ecoEXPLORE’s Entomology Season and share their observed insects towards an Entomology Badge at ecoexplore.net.

 

Sources Cited:

Hall, S.P.; Sullivan, J.B.; Petranka, J.W.; Backstrom, P.; and Howard, T. 2022. The Moths of North Carolina [Internet]. Raleigh (NC): North Carolina Biodiversity Project and North Carolina State Parks. Retrieved from https://auth1.dpr.ncparks.gov/moths/index.php.

INaturalist. iNaturalist. (n.d.). Retrieved from https://www.inaturalist.org.

Polinski, A.; Prins, E. (2021). Insects on Bald Head Island. Bald Head Island Conservancy.

Wall, D. W.; Buss, L. (2014, February). Tussock Moths – Orygia spp. Features Creatures. Entomology and Nematology Department, University of Florida. Retrieved from https://entnemdept.ufl.edu/creatures/urban/medical/tussock_moths.htm.

 

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