Connections: The Pawpaw Tree and the Zebra Swallowtail Butterfly

Asimina triloba and Eurytides marcellus

By Laura Seale

Editors: Devin Floyd, Clyde Kessler and Scott Jackson-Ricketts

A pair of survivors
The Zebra Swallowtail butterfly and the Common Pawpaw tree have been through a lot together. If you see one of these distinctive long-tailed butterflies glide past, it's likely there's a pawpaw patch nearby. The Zebra Swallowtail, Eurytides marcellus, is the only species of the genus Eurytides (the kite swallowtails) that makes its home in the temperate zones of North America. Other species from this genus live in subtropical zones. The sole source of food for the Zebra Swallowtail's caterpillars is the foliage, particularly the young leaves, of trees in the genus Asimina, the pawpaws. It happens that the Common Pawpaw, Asimina triloba, from the same family (Annonaceae) as the tropical custard apple and cherimoya, is also the only of the Asimina genus that is able to grow in this region of temperate North America, suggesting that the Zebra Swallowtails and the pawpaws have been co-evolving here since this region was very different than it is today.

A first good look
The first time I saw a Zebra Swallowtail, it was clinging with wings broadly spread, to a piece of tall grass at the edge of a cluster of pawpaw trees. Wind gusts from an approaching storm were keeping it grounded, which gave me ample time to admire and study its bold coloring. Its wings are more triangular in shape (with a span ranging from 2.5 to 4 inches) and its “tails” are longer and more slender than those of our other native swallowtails. Along with the zebra-stripes of black and greenish-white, the Zebra Swallowtail has two blue spots at the base of the upper surface of the hindwing, another bright red spot close to the body, and a red median stripe on the underside of the hindwing. The summer zebras are darker, with thicker black wing-stripes, and have longer tails than the ones that hatch early in spring.

Caterpillars' diet for self-defense
The Zebra Swallowtail female chooses young terminal leaves of the pawpaw on which to lay her eggs. The eggs are laid singly, one per leaf, because if the caterpillars encounter each other, they become cannibalistic. Those young paw paw leaves and their stem bark are especially rich in acetogenins, chemicals that make the foliage unpalatable to browsers, like deer and rabbits, and the leaf-munching caterpillars distasteful to potential predators. The Zebra Swallowtail mamas might get a little help from a pyralid moth called the Asimina webworm moth, Omphalocera munroei, that eats older leaves of the pawpaw to encourage growth of new acetogenin-rich terminal leaves.

Life as a zebra swallowtail
The Zebra Swallowtail larvae are hairless and appear somewhat humpbacked. When young, the caterpillar is dark with with many narrow transverse bands of black, yellow, and white. When older, they still have the stripey rings, but are greener, and often have one thicker black band across the top of the first abdominal segment. Like some other swallowtail caterpillars, the Zebra Swallowtail caterpillar can fend off predators by pushing out its osmeterium, which is a yellow, forked organ that emits foul-smelling odors. These odors are synthesized from essential oils, called terpenes, in the host plant. When ready, the caterpillars pupate under pawpaw leaves. Their pupae are green or brown and patterned to look like a curled leaf. After hatching, the females stay near the pawpaw patch, while the males can be seen patrolling for females, or puddling, sipping mineral rich water from moist soils. The adults nectar at a variety of flowers, including common milkweed, dogbane, redbud, and blackberry. It is notable that this butterfly only occasionally strays to elevations above 3000 ft. since it generally stays in the lower elevations where the pawpaws are.

Pawpaws' ploy for pollination
Of no interest to the Zebra Swallowtail butterfly are the pawpaw's flowers, as the butterflies do not pollinate the flowers or nectar on them. In fact, there is relatively sparse pollination of the early spring flowers, resulting in few fruits compared with the number of blooms. The flowers of Asimina triloba are reddish-brown, looking and smelling like rotting meat to attract carrion flies and beetles (and occasional Polygonia species butterflies). As pawpaws are not self-fertilizing, they require pollinators to travel from patch to patch. Local flies and beetles are not especially effective with this pollination, begging the question: “Was there once a more efficient pollinator, perhaps gone the way of the long-extinct mega-herbivores that roamed this continent in the past?”

Seeds can't move themselves
In addition to lacking ideal pollinators, pawpaws also lack an ideal method of seed dispersal. I have personally slipped (a la banana peels) down a hillside slick with fallen pawpaws, coating my seat with fermented pulp, wondering as I fell why there were so many of these sweet fruits rotting underfoot. It's possibly because our native Common Pawpaw is an anachronism, missing its original seed dispersing agents. The pawpaws may have evolved with the elephant-like mastodon and other extinct mega-fauna like the American camel and the giant ground sloth. The seeds are too large to be ingested, transported, and dropped in the dung of even our largest existing native herbivores, with the possible exception of the black bear. Deer show little interest in the leaves or the fruit, probably due to the plant’s chemical defenses. Since the extinction of mega-fauna, humans have likely been responsible for most of the redistribution of pawpaw seeds.

Patches of clones

One reason why pawpaws have continued to exist in this region, despite the spotty pollination and the lack of wide seed dispersal is their habit of cloning. The long-lived roots send up genetically identical suckers. The young trees are able to grow in the shade of the older ones, which eventually form the clonal “pawpaw patch.” Though the individual trees themselves tend to be short-lived, no one knows how old the root systems in pawpaw patches can get.
"Connections". Can you think of ways that this sketch says, "pawpaw"? The sketch includes a variety of indirect references to the pawpaw tree. (See bottom of article for some answers). Print the image above as a coloring sheet (PDF)

Native food staple

The first historical mention of pawpaws was in a 1541 report from an expedition of Spanish explorer, Hernando de Soto. His party observed Native Americans cultivating and eating pawpaws. John Lawson, an English explorer, wrote about encountering Native Americans using pawpaws in his 1709 book,
A New Voyage to Carolina: “ The Papau is not a large Tree. I think, I never saw one a Foot through; but has the broadest Leaf of any Tree in the Woods, and bears an Apple about the Bigness of a Hen's Egg, yellow, soft, and as sweet, as any thing can well be. They make rare Puddings of this Fruit.”

Small but chemically significant
Common Pawpaw trees often grow in the understory of a forest. They don't get very tall, their maximum height being about 40 feet. The bark is brown and relatively smooth, though covered with wart-like pores. The leaves are large, 5-11 inches long, and obovate in shape, which means they broaden towards the leaf tip. If you crush a leaf with your fingers, you'll find that it has an unpleasant smell (unless you like the smell of fresh asphalt). Chemical compounds from the pawpaw stem bark and ground seeds have been used medicinally for their insecticidal and anti-parasitic properties, and their annonaceous acetogenins are now being studied as a potential cancer treatment, as they seem to inhibit tumor cell growth.

A local fruit worth trying
Pawpaw fruits start out green, then ripen through yellow to a purplish-brown. They often grow in small clusters, which have a way of hiding under the large leaves. The fruits of the Pawpaw have custardy pulp, and 10-14 tough seeds that look like big brown beans. Some liken their flavor to banana or pineapple, though the ones I have eaten taste like a very mild soft mango. Around Central Virginia, the fruits ripen in mid to late August. People make them into puddings and pies. I have eaten pawpaws fresh, in ice cream, and in paw paw bread (recipe similar to banana bread). Cooking with them is more labor-intensive than using thick-skinned bananas or fruit with a convenient single pit, but since they are the closest thing to a locally grown, tropical-tasting fruit, and since I have a free source of pawpaws, they are worth the effort. Considered delectable by many, pawpaw fruits are not widely distributed in supermarkets due to the easily bruised flesh and short shelf-life of the ripe fruit. Large-scale commercial pawpaw cultivation schemes have not been successful so far, due to the difficulties with pollination. Maybe someday pawpaws will be available in grocery stores of every region, but for now they're an exclusive treat for to those lucky enough to find a pawpaw patch. Just follow the Zebra Swallowtails.



Some answers to the sketch "connections" question above:
  • The human in the sketch is a Native American child. Native Americans utilized the pawpaw tree as a food source.
  • The plant in the middle ground is Apocynum cannabinum (Indian hemp, hemp dogbane) and was a primary fiber material. It was used to make string, rope, bags, sacks, and many other things. It is not out of the question that a collection bag or basket constructed of Apocynum cannabinum fiber would have been used to collect pawpaw fruit.
  • The zebra swallowtail frequents Apocynum cannabinum for its nectar.
  • The pawpaw tree is the zebra swallowtail's only host plant. It's caterpillar can't survive without it.
  • Those are wild turkey feathers in her hair, and the wild turkey loves pawpaws fruit.
  • Her necklace might contain pawpaw seed beads. The seeds are beautiful and hard.
The sketch illustrates, in a simplifed way, the very circular nature of connections between things. A pawpaw tree can be communicated without actually showing it.

Moth Night, July 30, 2011

On Moth Night, July 30, in spite of intermittent rain showers, more than 20 people gathered at the Matthews Living History Farm Museum from 8:30 to 11:30 p.m. to look at moths and other night-flying insects attracted to black light/moth sheet setups. Bob Perkins and Cecelia Mathis photographed insects for later identification. Bob subsequently identified 24 moth species and some other insects. He is working on three moths that may or may not be identifiable. Highlights included a dobsonfly, a long-horned caddisfly, beautiful wood-nymph, showy emerald, and nais tiger moth.

Moths identified:
  • eastern grass-tubeworm, Acrolophus plumifrontella
  • black-shaded platynota, Platynota flavedana
  • hahncappsia marculenta, Hahncappsia marculenta
  • celery leaftier, Udea rubigalis
  • Basswood Leafroller Moth, Pantographa limata
  • sod webworm, Pediasia trisecta
  • bluegrass webworm moth, Parapediasia teterrella
  • red-headed inchworm angle moth, Macaria bisignata
  • pale-marked angle moth, Macaria signata
  • Canadian melanolophia moth, Melanolophia canadaria
  • showy emerald, Dichorda iridaria
  • idaea productata, Idaea productata
  • toothed brown carpet, Xanthorhoe lacustra
  • common eupithecia, Eupithecia miserulata
  • Isabella tiger moth, Pyrrharctia isabella
  • nais tiger moth, Apantesis nais
  • banded tussock moth, Halysidota tessellaris
  • hickory tussock moth, Lophocampa caryae
  • grayish zanclognatha, Zanclognatha pedipililas
  • faint-spotted palthis Moth, Palthis asopialis
  • clover Looper, Caenurgina crassiuscula
  • black-patched graylet, Hyperstrotia secta
  • black wedge-spot, Homophoberia apicosa
  • beautiful wood-nymph moth, Eudryas grata
Other Insects:
  • false katydid spp
  • field cricket spp
  • mayflies, at least two species
  • Caddisflies, several species
  • long-horned caddisfly, species of Leptoceridae family
  • stonefly, small species
  • dobsonfly
  • cabbage white (butterfly)
  • long-necked seed bug, Myodocha serripes
  • leafhoppers, several species
  • lady beetle spp
  • scarab beetles, several species

-Bob Perkins

A Passion for Moths--My 2010 Moth Big Year

Clymene Moth, Haploa clymene ©Merrill Lynch

Snowflakes are falling as I type. Winter has arrived in the High Country and, I'm afraid, the end of the moth season for 2010. So now is the time to summarize my season long quest to see as many species of moths as possible at a single location. I hope the following account of my mothing big year will be interesting and inspiring to those of you out there who share a passion for the nocturnal leps. (Image to right: Painted Lichen Moth, Hypoprepia fucosa ©Merrill Lynch)

I have been interested in moths for the past ten years or so (noting new species in my tattered copy of Covell) but only started keeping detailed records in 2009, shortly after moving to Watauga County. In 2010 it became an obsession when sometime in June I added up the species I had recorded for the year and was stunned that I had close to 300 species and summer had barely begun! I then set my first goal, 500 species, which seemed at the time both realistic and reasonably ambitious. When I hit 500 species in early August, I decided to just keep at it full bore and vowed to keep the lights on and check the sheets until the last moth flew (or I was evicted from the premises by my long suffering partner!). I was also inspired by the efforts of the Tennessee moth'ers who had gotten together in the spring and decided to undertake an ambitious effort to document all of the moths in their state in 2010. (Image above right: Ailanthus Webworm Moth, Atteva punctella ©Merrill Lynch)

Before I get into the details of the big year, let me just say that I find moths infinitely interesting. For one thing, they are beautiful insects that have an incredible diversity of shapes, patterns, and palettes--even the ones that at first glance appear brown and dull reveal intricate patterns and subtly beautiful colors at closer inspection. Sorry, diurnal lepsters, but butterflies don't have anything on moths! And another thing about moths. They are ubiquitous and abundant and exist in almost endless diversity filling every conceivable ecological niche. And they literally come to you--you don't have to go and chase them! Digital photography has really opened up the moth world to closer examination and has become an essential identification tool. (Image above right: Rosy Maple Moth, Dryocampa rubicunda ©Merrill Lynch)

In 2010, I recorded 632 species of moths in my backyard, starting with a Grote's Pinion (Lithophane grotei) on March 8 and ending with Acrolepiopsis heppneri (a micromoth in the family Acrolepiidae) on November 3. (Image below right: Io Moth, Automeris io ©Merrill Lynch)

Other Parts of this Article:

©J. Merrill Lynch
Echo Valley Farm
Watauga County, NC
Elevation: 3,400 feet

A Passion for Moths--Equipment

Dark-banded Geometer, Ecliptopera atricolorata ©Merrill Lynch

Equipment: My equipment consisted of 2 sheets lighted by one 160 MV lamp located in the front yard near a small stream; one towel mounted on the sheltered wall of the house under the porch roof, lighted by a single 15W fluorescent black light; and a porch light lighted by a 15W compact fluorescent white light. I also experimented with a sugar bait concoction that I painted on a tree in the front yard. I did this periodically throughout the season and was rewarded with at least a dozen species that never came in to my lights. (image above right is of the Ironweed Borer, Papaipema cerussata ©Merrill Lynch)

My general routine was to turn the lights on around sunset and check the sheets for 1-4 hours each night, first in the early evening between dusk and midnight and again in the early morning between 3-7am (pre-dawn), leaving the lights on all night. I tried to take multiple photographs of each moth that I did not recognize and also photos of fresh specimens of all species.for photodocumentation. (Image to the right: Skiff Moth, Prolimacodes badia ©Merrill Lynch)

All of my photographs were taken with a Panasonic GH-1 using a 45mm (90mm slr equivalent) macro lens. The images were downloaded daily into my computer where I would begin the arduous task of sorting and identifying the photos to species. The identification process sometimes took days and even weeks. I relied primarily on the images on Moth Photographers Group and Bugguide websites and also consulted moth guidebooks such as Covell's Moths of Eastern North America. Occasionally, I would send photos off for identification help, sometimes to Bugguide but also to moth experts. I took over 9,000 images during the season and have photodocumentation for about 80% of the 632 species identified. (Image above left: the Hebrew, Polygrammate hebraeicum ©Merrill Lynch)

I entered the data on an excel spreadsheet that I stumbled upon on the Internet which contained a database of over 1,600 species of moths recorded in the Great Smoky Mountains National Park. Over 90% of the moths I've recorded in Watauga County are in this database.

Other Parts of this Article

©J. Merrill Lynch
Echo Valley Farm
Watauga County, NC
Elevation: 3,400 feet

A Passion for Moths--Location

False Crocus Geometer, Xanthotype urticaria ©Merrill Lynch

Location: All moths were recorded in my yard or in a few instances at mobile light stations set up on my property within a 1/4 mile of my house. My farm is located in northern Watauga County, NC about 15 miles north of Boone and less than one mile from the Tennessee border. It is located in the headwaters of the North Fork of the New River and is about 3,400 feet elevation. Snake Mountain (elevation--5,580 feet) is the dominant local topographic feature; the summit is about 3 miles due south. Habitat is early to mid-successional mesic northern hardwoods (containing patches of older growth forest) with a narrow open riparian zone and nearby pastures. The area around my property is very rural and dominated by a mosaic of open pasture and hardwood forest with abundant small streams and springs/seepages. The only evergreens are scattered Fraser fir christmas tree plantations and planted white pine stands.

Other Parts of this Article:

©J. Merrill Lynch
Echo Valley Farm
Watauga County, NC
Elevation: 3,400 feet

A Passion for Moths--Summary

(Polyphemus moth, Antheraea polyphemus ©Merrill Lynch)

Summary: I kept track of the nights that I actually checked the sheets and photographed moths, by month. The tally (monthly species total followed by mothing nights) is as follows:
(image to the right, The Herald, Scoliopteryx libatrix ©Merrill Lynch)

March: 9 spp; 7 nights;
April: 55 spp; 20 nights;
May: 146 spp; 20 nights;
June: approx. 200 spp; 15 nights;
July: 272 spp; 30 nights;
August: 214 spp; 28 nights;
September: 187 spp; 24 nights;
October: 87 spp; 22 nights;
November: 7 spp. 2 nights.
Grand Total: 632 spp; 168 observation nights.

The first moth of the season was Grote's Pinion (Lithophane grotei) seen at my sugar maple sap buckets on March 8 (with a foot of snow still on the ground!). Moths were few and far between until the first really mild nights of mid-late April when species diversity and numbers increased substantially. My first exciting find was an Immigrant Pinion (Lithophane oriunda) seen at my sugar bait station in early April. Recognizing its rarity, I sent off pics to various experts who corroborated the identification and confirmed the first record for this species in North Carolina! May and June brought an endless number of new species including many micros and many geometers. They also brought the first big boys, the larger sphinx and saturn moths. July was the peak month of moth diversity with 272 species recorded. August brought the first of the fall flying moths such as the borers (genus Papaipema) and September/October heralded the arrival of various noctuids collectively known as darts, pinions, and sallows. One of my favorite moths, the Large Tolype, made multiple appearances during these months. The final moth of the season was Acrolepiopsis heppneri, an interesting micromoth in the obscure family Acrolepiidae, noted on November 3.

Of the 632 species, 209 species were the so-called micros- families such as the torts (Tortricidae), grass-veneer moths (Crambidae), pyralids (Pyralidae), and plume moths (Pterophoridae)--122 species of geometers (Geometridae), 13 sphinx moths (Sphingidae), 24 prominents (Notodontidae), 19 tiger moths (Arctiidae), and 221 species of owlet moths (Noctuidae). One of my favorite groups, the Underwings (genus Catocala), were represented by 16 species. (image above left: Locust Underwing, Euparthenos nubilis ©Merrill Lynch)

I should mention that I missed a number of day-flying moths that are not attracted to lights such as the wasp mimics in the family Sesiidae, some of the day-flying sphinxes such as bumblebee clearwing, and many others. I also do not claim that my list is 100% accurate--in fact, I'm sure there are some mis-id's. I tried to be conservative and only record those species I was reasonably sure about and in some cases I left the identification at the genus level. But moth identification can be very challenging and there are many pitfalls one must traverse in the process: bad lighting or angle in the photograph can obscure important details; many species can only be identified by genitalic dissection and are visually inseparable; many species are not represented by photos (or the photos are low quality) on the various websites; some species are highly variable and come in many different color forms; many moths that are worn and have lost many of their scales simply cannot be identified; etc. I'm guessing that of the total number of moth images that I took over the season, unidentified images amounted to about 5-10 % of the total. (image above right: Giant Leopard Moth, Hypercompe scribonia ©Merrill Lynch)

To put my record in perspective, there are probably at least 2,400 species of moths in North Carolina; however, no one knows for sure because there is no official published list (although I hear rumors that Steve Hall at the NC Natural Heritage Program is working on this). This compares to 174 species of butterflies known in the state. Parker Backstrom, an avid moth'er in Chatham County, has recorded, I believe, around 700 species in and around his property over several years. Bob Patterson in Maryland probably holds the record for the most moths recorded at a single site--1000+ species-- but his record is cumulative over many years. I am not aware of anyone who has attempted a big year for moths but I'd be interested in hearing about it if anyone knows.

I should also say that I don't think my location is particularly exceptional in terms of moth diversity. I am fortunate to live in the country and have an abundance of natural habitats around me but I think my number could easily be duplicated (or exceeded) by anybody dedicated and crazy enough to devote the necessary time and energy required. Dave Beadle, the author of the upcoming field guide to moths, tells me that he has recorded over 500 species in his tiny backyard in downtown Toronto, Canada that is less than 100 square feet!

I want to thank Bo Sullivan, Parker Backstrom, Dave Beadle and Steve Hall for their inspiration, camaraderie, and identification assistance. Special thanks go to my partner, Gabby Call, for her infinite patience, understanding and encouragement. Thanks also are due all of the folks on the North Carolina and Tennessee moth list serves who provided much inspiration and encouragement.

Looking back on the year, it has been a thrill to observe and learn about such an amazing diversity of creatures, literally at my doorstep. Beauty and the diversity of life exemplified by tiny creatures that are right in front of us but we know so little about. I've developed a greater appreciation for the small things and hope that others will too. Moths are just cool, period. I hope that all of you out there who are already bitten will share your passion with others. And for those of you who have not paid much attention to moths, I hope you will give them a second look. I'm eagerly anticipating the arrival of Dave Beadle's moth guide due in 2012-- think back ten years ago when butterflying took off after publication of Glassberg's guide. And there is so much potential for folks to make contributions to science by simply observing and keeping records of these creatures; even basic life history information (flight season, food plants, etc) for many species is not known. And you never know, you may have a new species unknown to science waiting to be discovered right in your backyard. I can't imagine anything more exciting than that possibility. And finally, the most important thing to remember is that moths (and most other insects) exist in such profusion because of their long and intricate co-evolution with the plant kingdom--the conservation of biodiversity is the most important task and responsibility that we humans face.

Other Parts of this Article:

©J. Merrill Lynch
Echo Valley Farm
Watauga County, NC
Elevation: 3,400 feet

Hornworms or hummers?

My wife and I have devoted a lot of effort to providing plants for wildlife to utilize for food and shelter. I greatly prefer to have a plant provide nectar for hummingbirds than to put out a feeder with sugar water. Coral or trumpet honeysuckle (Lonicera sempervirens) is a native species that provides a beautiful red flower with abundant nectar for hummingbirds (see photo above). This seems to be an unequivocal win for the garden since it is beautiful, hardy, and highly attractive to hummingbirds. But today I discovered the "rest of the story" as it pertains to the biology of this wonderful honeysuckle.

As I sat rocking on our porch without a care in the world, I suddenly noticed something troubling- there were bare spots on our two honeysuckle vines and tell-tale small dark pellets on the ground underneath. The pellets seemed to be "frass" or caterpillar poop and this indicated something was eating our valuable vines! A quick search and about 10 minutes picking produced the haul shown in the photograph of a group of caterpillars, mostly green but a few brown. A close-up of one of the more common green ones (see photo below right) indicated that this was clearly a hornworm with a terminal harmless spine. I checked this out in the "bible" of caterpillar identification (Wagner's "Caterpillars of Eastern North America") and found a match with the snowberry clearwing sphinx moth. This moth in fact resembles a hummingbird in its flight characteristics and feeding on nectar, but mimics a bumblebee as a means of protection from avian predators.

So here I had a conundrum- some very interesting caterpillars of a species that I value were competing with both hummingbirds and their own adult stage by eating the plant that produces their nectar. My solution for the moment is to pick off all the caterpillars that I can find (far from an easy chore since they are VERY well camouflaged- green and subtly counter-shaded to blend in extremely well with the foliage) and put them in a container where I will feed them on less valuable honeysuckles until they get ready to pupate, when I will release them.

So what have we learned- that once again Nature is more complex than our simple mindsets, and that manipulation of plants for our purposes is often diverted to other ends? This provides an education for us to remain open to new ideas and to value this complexity and not to find it frustrating. Indeed it is exciting that the unexpected can break out and astound us- we have only to be observant and find wonder in the events as they unfold. I also learned that I can sometimes learn more while rocking on the porch and contemplating Nature from that perspective than hiking in the woods and fields!

Bill Dunson
Galax, VA & Englewood, FL

Beware fuzzy caterpillars!

We have planted many hundreds of trees and shrubs on our property to encourage wildlife of all sorts, so I keep a careful eye out for pests that eat these plants. Some of the worse problems are due to insects that come in groups, such as caterpillars of various moths. I am used to dealing with army worms and web worms but came across a new enemy recently. Groups of hungry caterpillars appeared on our treasured black walnut trees (and sumac also) and started a full-scale attack (see photo above). In their young stage they were white with black spots and a black head, and were quite hairy. Now a fuzzy caterpillar often means "KEEP AWAY" since the hairs can be irritating and even toxic. These turned out to be hickory tussock moths or hickory tiger moths which are well known to possess stinging hairs and even to be toxic for birds to eat. They group together, likely with their siblings that hatched from their mother's eggs, and remain together for some time until they get much larger when they live alone (see photo below, of a much older caterpillar from our yard- not a typical coloration- often they are more black and white).
It is interesting to think about why not only insects but many types of animals group together in flocks or swarms. It is usually considered to be a defense, potentially to confuse and divert the attack of predators. In the case of these caterpillars, it is also likely that distasteful and/or toxic creatures ban together with siblings to gain an additional advantage if a predator does attack and learns to avoid this color pattern in the future. Siblings that share many of the same genes will benefit more by being together with their brothers and sisters than with strangers, if they are attacked and some are sacrificed to teach the predator to avoid the others.

Caterpillars have a variety of defenses other than stinging hairs and toxic flesh. They tend to be active at night and group together in daytime under protective webs. When I touched the leaf on which the young hickory tussock moths were sitting, a surprising thing happened- numbers of caterpillars began to drop down to the ground quickly on web lines (see photo). You might wonder why this would be necessary when these caterpillars seem to be so well protected. However virtually all good defenses have spawned a specialized predator that can circumvent the defensive strategy- in this case it is the yellow-billed cuckoo (see photo) which is a fuzzy caterpillar eater. Not coincidentally we have noticed far more cuckoos on our property this year than last when caterpillars were not so numerous. So the hickory tussock moth caterpillars drop from the tree at the slightest indication of a cuckoo being present, and can then crawl back into the tree after the cuckoo leaves.

The intricate natural history of something so seemingly inconsequential as a tiger moth caterpillar tells us once again that the adaptations of this larval moth are subject to very specific design criteria to maximize its chances of survival and subsequent reproduction. So even if we destroy some of these creatures that eat our yard plants, we cannot fail to marvel at their remarkable methods of existence.

Bill Dunson
Galax, VA & Englewood, FL

The bagworm- it builds a house and comes to eat your plants

I came across an old acquaintance today while walking near Arcadia,FL, the bagworm. This curious caterpillar of a moth with an unpronounceable name, Thyridopteryx ephemeraeformis, has a very strange habit that makes it very distinctive and easy to identify. As its name implies it makes a case or bag out of silk and bits of plant material and crawls around with only its head and front end exposed. The bag is an ingenious contraption of small pieces of stems and leaves of the plant that the caterpillar is feeding on. In this case the plant was a hog plum, but this moth feeds on a wide variety of plants, causing it to be a serious pest in some situations. Clearly the bag serves to protect the caterpillar in two ways; it is both a camouflage and a physical protection against attack by predators such as birds. However the caterpillar must come at least partly out to feed and can be attacked then.

For some amazing photographs of the Bagworm check out Victor Engel's work: http://bugguide.net/node/view/135982/bgimage

The breeding habits of the bagworm are quite peculiar- the female is flightless and remains in the case for her entire adult life. The adult male must fly to her location and fertilize her eggs, which are laid in the bag where they remain all Winter. They hatch in the Spring and the young larvae disperse and make their first bags. Although this species is named for a mayfly (which the adult male slightly resembles), there is a greater resemblance to the caddisfly larvae which lives in water but also constructs a case out of sticks, sand or small pebbles. Now although caddisflies and bagworms are somewhat related, they are in separate groups and it seems unlikely that a common ancestor had the habit of constructing larval cases. So we may conclude that their shared habit of constructing cases for their larvae is probably an example of separate but convergent evolution.

So if you see bagworms on one of your valued plants you might just want to move them someplace else since they can do some serious damage. The simplest time to do this is in Winter when the bags contain hundreds of eggs and can easily be picked off the plants. But in any event let us marvel once again at the remarkable diversity of nature.

Bill Dunson
Englewood, FL & Galax, VA

Sallows & Other Moths

Over the past few weeks in the evenings, whenever I turn the porch lights on, sallow moths gather.
They flutter near the screen door, and along the wall--some station themselves in little seams in the wood paneling, others perch there as if frozen into the light.

The most common is Bicolored Sallow (Sunira bicolorago). Several arrive every warm evening, little swarms of orangish yellow edged in a thin purple. As many as twenty or so zone in on the light by the front door. Two Octobers ago, I saw more than fifty, an outright crazy swirl of them that would hurdle and joust about, when I would get close. But mostly these moths just wait there, owned by the light.

A few other sallows have graced the wall:

Footpath Sallow (Metaxaglaea semitaria)
Battered Sallow (Sunira verberata)
Three-spotted Sallow (Eupsilia tristigmata)

A few other species of sallows have visited too, but I haven't keyed them out.

Other moths in the last few evenings:

Implicit Arches (Lacinipolia implicata)
Armyworm Moth (Pseudaletia unipuncta)

And likewise, several that I can't identify.

For most of October, I felt a special joy in seeing Rose Hooktip Moths (Oreta rosea). It is a favorite, a rather muted orangish rose color with a few darker lines, and of course the wings have a wonderful hook at the wingtips...at least that's the color pattern of the ones resting on the wall and screen door, up to six or seven on more than one evening.

I will have to start focusing a camera at them, or sketching some pictures and share those some time in the future. Right now, you can visit many wonderful moth web sites...I like the moth photo pages of Bob Patterson, and others at the moth photographers group web site....


I don't like to leave lights on very long, extra on electric bill, but more I think it disrupts their moth schedules. They should be foraging, flitting, courting, mating, ovipositing etc., not hunkered at my house, mesmerized and captured by porch lights. I turn the lights off soon as everyone is home from their evening travels.

What moths are you all finding these November nights?