Giant Silkmoths

We were fortunate to have hosted three species of giant silkmoths (family Saturniidae) in Butterfly Magic this year. They are spectacular insects, but so unique and short-lived that one cannot generalize to moths as a whole from their life cycle and behavior.

Estimates differ as to how many species are in the Saturniidae, but somewhere between 1,300 and 1,500 is fairly accurate. Gene sequencing could result in more or fewer species than currently recognized. Giant Silkmoths are found the world over in forest habitats, but are especially diverse in the neotropics (Mexico, Central and South America). You are probably already familiar with some U.S. species: the Luna Moth, Cecropia Moth, Polyphemus Moth, Royal Walnut Moth, Imperial Moth, and Cynthia Moth. Not all the silkmoths are giants. Buck moths (genus Hemileuca) are much smaller, and fly during the day.

The adult moths do not feed. They have vestigial mouthparts at best and fuel their flight on fat reserves accumulated as caterpillars. Consequently, the caterpillars of giant silkmoths are large and heavy at maturity. The “hickory horned devil,” larva of the Royal Walnut Moth, approaches the size of a frankfurter. It looks menacing but is harmless.

Meanwhile, the larvae of other silkmoths are studded in venomous spines. Beware the caterpillars of buck moths (I can attest from personal experience!), the io moth, and especially the South American Lonomia (see also more recent articles in medical journals).

The Forbes Moth, Rothschildia lebeau forbesi, is frequently mistaken for an Atlas Moth by our visitors. Both species have “windows” in their wings that are devoid of scales. The Forbes Moth ranges from the Lower Rio Grande Valley through much of eastern Mexico and south to Brazil. Relatives of this moth figure prominently in the culture of indigenous peoples. Bushels of cocoons are harvested to make rattles worn on the ankles during ceremonial dances.

The African Moon Moth, Argema mimosa, occurs over most of sub-Saharan Africa. Their cocoons are distinctive: compact, and made of dense silk with numerous small perforations. The adult moths are spectacular: a wingspan averaging 125 mm, yellowish green in color with long, streaming “tails” on the hindwings. What purpose those tails serve is open to speculation, but perhaps it further camouflages the insect when it is at rest among foliage.

Last but not least is the Atlas Moth, Attacus atlas, a real giant with a wingspan of 240 mm (compare that to the Forbes Moth, only 90-100 mm from wingtip to wingtip). The Atlas Moth is widely distributed, from India to Hong Kong, tropical Asia in general, plus Taiwan and Indonesia. The front wings have a conspicuous lobe with markings that suggest the head of a serpent, but whether this is real mimicry or not is debatable.

The adult females of all the silkmoths rarely stray far from their cocoons after emerging. They invest most of their energy in egg production, so instead of exerting calories in flight, they simply sit and emit a species-specific sexual attractant called a pheromone. This scent, while usually imperceptible to us, is potent when it comes to drawing males. The males, with broad wings and streamlined bodies, use their sensitive antennae to home in on the pheromones, following the scent trail up to a mile or more to find its source. Females, once mated, will then finally fly to appropriate host trees and deposit their eggs. Even unmated females will dump their eggs in great quantities, as is often seen in our greenhouse. Both genders live only a few days, assuming they can avoid predation by bats.

Breeding silkmoths in captivity is becoming quite the hobby and cottage industry. My friend Liz Day has a web page devoted to helpful hints for rearing common eastern U.S. species. Considering the threats faced by these magnificent moths, from suburban sprawl and light pollution to introduced parasites, our domestic species could use some help.

I would like to conclude by recommending Wings of Paradise by John Cody, published by University of North Carolina Press, 1996. Cody renders giant silkmoths in stunning watercolor paintings. He features all three species in the greenhouse, plus scores more. The art is complemented with anecdotes and factual information.

Spring (Butterfly) Beauties

Spring has definitely “sprung” here at the Tucson Botanical Gardens. Many flowers are in bloom, and native butterflies are taking full advantage of the bounty of nectar. We are now up to forty (yes, 40) confirmed butterfly species seen on the grounds. Recent observations have yielded some surprises, including one supposedly rare species of skipper.

The “usual suspects” are here: Pipevine Swallowtail, Giant Swallowtail, Checkered White, Southern Dogface, Sleepy Orange, Dainty Sulphur, Gray Hairstreak (image above), Marine
Blue, Reakirt’s Blue, Fatal Metalmark, Gulf Fritillary, Texan Crescent, American Snout, and Painted Lady. What is new, then? Plenty.

One of the more startling species I spotted a couple weeks ago was a Desert Orangetip, Anthocharis cethura. Just as I focused my camera on it, away it flew. That figures. I haven’t seen one since, either.

Another mild surprise was a Mourning Cloak, Nymphalis antiopa (image below). This large, black butterfly with a creamy border is more typical of riparian areas since it feeds on willow in the caterpillar stage. This male specimen was frequenting the bird garden. He perched where he had a good vantage point and darted out after any intruder, especially other butterflies like Pipevine Swallowtails. After a brief chase he returned to the same area he started from. He even alighted on a visitor’s ballcap while I was watching.

The real shockers have come from the skippers in the family Hesperiidae. Sure, the Fiery Skipper, Orange Skipperling, Common Checkered-Skipper, and Eufala Skipper are common enough, but I’ve seen other species that I would not expect here. The first of these was a Sleepy Duskywing, Erynnis brizo, seen on March 4 (image below). This species feeds on oak as a caterpillar, so it really belongs a couple of thousand feet higher in elevation. There it was, though, on a Dalea blossom in the butterfly garden.

The Funereal Duskywing, Erynnis funeralis, is a much more likely species here at the Gardens. I finally spotted one on March 19, but failed to get a picture. This fast-flying skipper is fairly large. Mostly black, it has a blazing white border along the edge of its hind wing which makes it easily identifiable.

Another surprise was an Arizona Powdered-Skipper, Systasea zampa (image above), sitting on a brick in the barrio garden late in the afternoon of March 6. I initially figured it for a Fatal Metalmark, to which it bears superficial resemblance.

The Golden-headed Scallopwing, Staphylus ceos, also resembles a metalmark at first glance.

The most amazing of all the spring skippers was a Violet-clouded Skipper, Lerodea arabus. It is relatively non-descript (see image below), save for a distinct dark brown patch on the underside of its hind wing. Certainly no violet to be seen! You would think that this would be among the more abundant of butterfly species given that the caterpillar feeds on Bermuda grass, barnyard grass, and other weedy plants. Instead, most reference books list it as “rare.”

Last but not least, I added a species by proxy. One of the visitors to the Butterfly Magic greenhouse, Carolyn Vieira, mentioned to me that she also takes pictures of butterflies on the TBG grounds. I told her I had yet to see a Great Purple Hairstreak, Atlides halesus, and as luck would have it she had a picture she took a couple years ago or so. I still expect to see this spectacular butterfly here myself, but it is nice to have an existing record.

The diversity of wildlife to be found at the Tucson Botanical Gardens continues to astound me. Just in cursory observation I’m closing in on 200 species of animals, from arthropods to apes (we Homo sapiens). The wide variety of plants, and the constant watering no doubt provides a literal oasis for all.

Butterfly Love

Spring is in the air here in Tucson, Arizona, and apparently the thoughts of butterflies are turning to love. I wrote the following for the Valentine’s Day issue of the volunteer newsletter at the Tucson Botanical Gardens, but cruising the grounds this past week I saw plenty of native butterflies in “action,” so to speak, like this pair of Giant Swallowtails outside our administration building.

Visitors to Butterfly Magic will never fail to notice when two butterflies are conjoined, and will ask you what is going on with that. Well, ok, so the butterflies themselves are not shy when it comes to courtship and sex. They have a limited amount of time to find acceptable mates and produce the next generation.

Among the more dazzling behaviors butterflies engage in is courtship. There are great differences in courtship behavior from family to family, and even species to species, but you can easily recognize certain postures and flight styles as romance-intended. Females may advertise their availability by perching with wings open and abdomen slightly raised. She may also “call” males by releasing a special chemical called a pheromone. Males detect the wind-wafted scent with their antennae and then quickly recognize her visually. Male giant silkmoths like the African Moon Moth and the Forbes Moth can home in on a female from up to a mile away (maybe even longer) by following her pheromone trail.

Male butterflies of many species have pheromones, too, designed to communicate individual fitness to a potential mate. Once he locates a female the male must convince her he is a worthy investment. He may do this by following her in flight until she lands, then hovering over her and showering her with his own “cologne” emitted from special scent patches on his wings, or from “hair pencils,” glands that he extrudes from the rear of his abdomen. Males of some Heliconiinae (longwings) go a step further and sprinkle an anti-aphrodisiac once mating has occurred. This discourages other males from usurping his genetic investment in that particular female’s offspring.

Should the female be disinterested in a suitor, she changes her posture, pointing her abdomen nearly straight up and essentially “mooning” the male.

The pursuit and hovering displays are characteristic of the male Priamus Birdwings and the Heliconius longwings. Morphos are less elegant. Males will land next to perched females and aggressively “nudge” them into compliance. Watch as a male bends his abdomen forward in an attempt to copulate.

Compatible males and females may eventually couple, tail-to-tail, facing in opposite directions. Males might even hang limply from the female as she remains perched. Occasionally the pair will even take flight, one of them carrying the other. Butterflies can remain coupled for as little as a few minutes to several hours. We had one pair of Priamus Birdwings (shown above) engaged for so long that the male actually perished while still connected to the female. While lengthy mating leaves both butterflies vulnerable to predation, it also prevents other males from mating with a given female, increasing the odds that the male will see some of his genes represented in the next generation produced by that female. Nature is full of such trade-offs.

Butterflies have the same sex organs as other animals, but they go by different names. The male penis is called an aedeagus (ee-dee-AY-gus). The shape and configuration of the aedeagus varies from species to species, largely preventing hybridization between different species. He also has claspers, the external genitalia that hold the couple together during sex. The female has a vagina (the “bursa copulatrix”), but also has a “receptaculum seminis” or “spermatheca,” a sac that stores sperm. Her eggs will not be fertilized until she lays them.

Whew! I managed to get through all that without even talking about contraception and the Butterfly Vatican.

A pair of Texan Crescents is shown above.

Butterfly Time (Part 1)

The seventh annual installment of “Butterfly Magic” opened last Monday at the Tucson Botanical Gardens. The live, flying butterflies (and a few moths) will be occupying the tropical greenhouse through April, 2011, open daily from 9:30 AM until 3:00 PM, save for the obvious holidays.

This year I find myself in the position of Assistant Butterfly Curator, but Dr. Elizabeth Willott, Curator of Butterflies, is the person responsible for the success of this event. We also owe an enormous debt of gratitude to the many volunteers who actually staff the exhibit day in and day out, and who ensure that the butterflies make it from the Chrysalis Room to the greenhouse. More importantly, they make sure no butterflies escape the confines of the greenhouse. They also interpret the exhibit, sharing their knowledge of the insects with visitors and making sure our human guests have a pleasant experience. The volunteers also protect the butterflies from unintentional harm at the hands of overzealous visitors.

Our first shipment of butterfly chrysalids (pupae) arrived Friday, October 1. Elizabeth and I picked them up from the nearby FedEx store where they arrived via overnight shipment from a butterfly distributor in Denver, Colorado. At some point I hope to document the receiving and handling such shipments and sharing that with all of you. It is a very labor-intensive process. October first’s extraordinarily hot temperatures may have spelled doom for many of the specimens in the shipment. We humans were certainly sweating our way through sorting and pinning them. I finished the day pretty dehydrated and a bit light-headed.

The end result is worth the trouble, though. Among our first crop of butterflies was the Danaid Eggfly or “Mimic,” Hypolimnas misippus. The females (see image above) mimic the African Monarch and other distasteful butterflies. The males, on the other hand, look radically different (image below). Yes, those really are the same species!

Among the most populous of our new arrivals is the Mocker Swallowtail, Papilio dardanus. As you might have guessed from the common name this, too, is a species exhibiting dramatic sexual dimorphism. The females lack tails, looking very much like the milkweed butterflies they are impersonating. Males have the familiar “tails” on the wings and are boldly marked with black and white on the top side of the wings. Here is a mating pair (below).

Enjoy this species while you can, as it was denied on our United States Department of Agriculture (USDA) permit this year. Fortunately, that decision was not retroactive to our current permit with our U.S. distributor. We will be unable to import Papilio dardanus directly from its native Africa from now on, however. The caterpillars feed on citrus and are thus deemed a potential threat to that industry.

Yet another spectacular butterfly on show is the Flame-bordered Charaxes, Charaxes protoclea. It, too, is a native of Africa. This is a powerful flier, its robust body packed with muscles to operate those fiery wings.

Be sure to check out images of some additional species in Part 2 of this article, over at ”Sense of Misplaced”. Thanks, hope to see you pass through the Tucson Botanical Gardens one of these days.

Update.

Once again I find myself apologizing for the relatively sporadic nature of my posts here lately. No excuses, really, though I have been working rather random hours at the Tucson Botanical Gardens, and consequently eating randomly, sleeping randomly, and writing randomly. Maybe I need to take a class on time management.

I also just concluded a project in which I reviewed chapters for a forthcoming self-published book on the natural history of Virginia Beach, Virginia, by Scott Bastian. He has been a delight to work with, and he will be turning out a pretty unique book that has a wealth of information stretching far beyond the locality of Virginia Beach. You'll hear more about this once it is off the presses.

A relative lack of rain this year in Arizona (except for the area immediately adjacent to the Mexican border) has meant that many insects have been lacking, or at least less numerous, than usual. Perhaps because the Tucson Botanical Gardens is heavily watered, I have found a surprising diversity of things there, and expect the trend to continue through October.

Best wishes to my readers for a fruitful fall of exploring, image-taking, and enjoyment of autumn colors.

(Wild) Butterfly Magic

Anyone visiting the Tucson Botanical Gardens lately who is disappointed to learn that the Butterfly Magic event begins in October hasn’t been paying enough attention to the butterflies that are flying freely around the garden outside of the tropical greenhouse. I tallied twenty-two species over the past month, most of those seen in the last week or so. Here’s the list:

• Pipevine Swallowtail, Battus philenor
• Giant Swallowtail, Papilio cresphontes

• Checkered White, Pontia protodice
• Southern Dogface, Colias cesonia
• Sleepy Orange, Eurema nicippe
• Dainty Sulphur, Nathalis iole
• Cloudless Sulphur, Phoebis sennae
• Gray Hairstreak, Strymon melinus
• Leda Ministreak, Ministrymon leda

• Marine Blue, Leptotes marina
• Western Pygmy-Blue, Brephidium exile
• Reakirt’s Blue, Hemiargus isola
• Fatal Metalmark, Calephelis nemesis
• Palmer’s Metalmark, Apodemia palmeri

• Gulf Fritillary, Agraulis vanillae
• Variegated Fritillary, Euptoieta Claudia

• Empress Leilia, Asterocampa leilia
• American Snout, Libytheana carinenta
• Queen, Danaus gilippus
• Common Sootywing, Pholisora Catullus
• Fiery Skipper, Hylephila phyleus
• Orange Skipperling, Copaeodes aurantiaca

The TBG has a dedicated butterfly garden, but there is such a diversity of plants on the grounds that something is blooming somewhere almost all the time. Water and shade are also plentiful, which benefits both the butterflies and the comfort of human patrons.

Please visit the Tucson Botanical Gardens whenever you can. There is literally something for everyone, from a Children’s Garden to a Zen Garden, to the Tropical Greenhouse. You can even bring the dog on Tuesday mornings, or stay late on the Third Thursday when you can hear a musical performance.

News Flash

I will be starting a new, part-time job shortly at the Tucson Botanical Gardens. My title will be "Assistant Butterfly Curator" for the Butterfly Magic exhibit of live butterflies that runs from October through April. Elizabeth Willott, Curator of Butterflies, will be my supervisor there. I am very much looking forward to learning how to better train and manage volunteers, which will account for most of my duties.

I am still actively seeking full-time work online, in media, and museums, but am very grateful to TBG for extending me this offer. I will still have time to continue freelance work as well.

Butterfly Magic in Tucson

Last Sunday, January 21, I visited the “Butterfly Magic” exhibit of live tropical butterflies at the Tucson Botanical Gardens. This is the sixth anniversary of what has become an annual event, lasting several months. The current incarnation opened on October 12, 2009 and will continue through April 30, 2010.

Despite being dramatically smaller than dedicated butterfly houses like Magic Wings, the confines of the tropical greenhouse boast a surprising diversity of species. I spent more than five hours there and was finding “new” species right up until my departure. The volunteers for the exhibit release newly-emerged specimens at least three times per day, but many of the butterflies already in the room are cryptic enough to escape detection by the average visitor.

One of the unfortunate aspects of any butterfly display facility is the difficulty in taking images of the butterflies in as “natural” a setting as possible. Some of the insects seem to park themselves at those ugly feeding stations, making for far less than a photogenic opportunity.

Then it never fails that the best shot you could possibly hope for also includes an out-of-focus person in the background wearing bright clothing. How do you politely say “Ma’am, you’re in my shot?” Mostly, you wait for the background personnel to clear and hope the butterfly has waited as well.

The Tucson Botanical Gardens solve part of the photographic problem by setting aside time strictly for photographers, without competing crowds, but it is at the end of the day when the incoming sunlight is not particularly good, and they charge double the normal admission price.

Still, one can’t complain, and you can still get stunning images of a great many species. Just be prepared for the obligatory heat and humidity, and understand it will take your camera lens at least ten minutes to become steam-free. I’ll be sharing more of my own images in the coming weeks for those who want to live vicariously through my blog.

Each trip promises to be different because the TBG has scheduled different shipments of butterflies from different parts of the world each month. October and November of last year featured native butterflies from Arizona and other parts of the southern U.S. December’s butterflies were from Australia. January was for African species, and February will spotlight Asian butterflies. March and April will be a veritable cornucopia of species from throughout the world.

Admission to this special show runs $12.00 US for adults, $6.50 for children 4-12 years of age, and is free for children 3 and under. Hours of the exhibit are 10 AM – 3 PM daily. The gardens themselves are open from 8:30 AM – 4:30 PM, and worth the visit all by themselves. The TBG has been rightly called an “oasis” in the heart of midtown Tucson. Enjoy!

NOTE: I now monitor the comments on my blogs, but have been experiencing browser failure in my Yahoo Mail recently. There may be a substantial lag between when comments are posted and when they are approved. My sincerest apologies for the inconvenience.