"Giant Swallowtail" refers to different butterflies in different countries. Jamaica has a Giant Swallowtail that is more gigantic than Heraclides cresphontes. Florida's Giant Swallowtail is, however, the biggest butterfly normally found in the Eastern States.
Photo by Aabge001, February, Florida. For a long time, the Monarch and the Tiger Swallowtail could claim to be the biggest butterflies most people in the Eastern States would ever see. (They have different shapes, and individuals vary; some Monarchs, including all that I've seen, are bigger than some Tiger Swallowtails, but Google says Tiger Swallowtails hold the records.) The Giant Swallowtail is bigger than either--at least in Florida.
Photo by Jim at MarylandBiodiversity.com, taken in Maryland, in July. In the twentieth century this species was reported only from Florida and south Texas, but it has now been found in most of North America.
Photos by Terrymortier, Wisconsin.
Photo by Robert Rold, Kentucky.
For a long time it was believed that the Giant Swallowtails that occasionally infest California orange groves were straying H. cresphontes, but the caterpillars look different at some stages and the adults' tail ends look different, so they are now classified as a separate species, H. rumiko. We shall consider the Rumikos, or Western Giants, in their turn.
Meanwhile, this chart (scroll down as necessary to see the chart) explains the typical minor differences in color markings on cresphontes and rumiko. H. thoas typically has an even wider yellow stripe across the upper forewings. Swallowtails can be variable. It can be hard to tell the species of a living, flapping butterfly. Reportedly the tail ends of the males can be identified by touch, but who wants to touch a butterfly's tail end? (They don't sting but they do stink--or, depending on your species, smell irresistible. People who handle moths and butterflies have been mobbed.)
H. rumiko was identified after the tradition of naming Swallowtails in honor of characters in literature had broken up; it was named after a researcher's wife. H. cresphontes, however, was named early enough for its name to make sense at least as wordplay. Heraclides means descendants of Heracles (the Greek form of the name) or Hercules (the Latin form). Cresphontes was said to be the descendant of that character. Aristodemus and Temenos, his brothers, are also commemorated in the names of Heraclides species. One of the butterflies' favorite food plants is Zanthoxylon clava-herculis, or Hercules' Club. Humans notice them more often on citrus trees, but Zanthoxylon is classified in the citrus family.
The easiest way to tell the Eastern Giant from the King Swallowtail, H. thoas, in places where both are found, is to inspect their tail segments under a magnifying glass. Traditionally very large black and yellow Swallowtails found in Florida have been presumed to be cresphontes. This is not necessarily always the case. Butterflies get around. Heraclides thoas is normally found further south, but has been found in Florida and Texas. Heraclides cresphontes have strayed up into the Northern States and even Canada. There is a variant form called pennsylvanicus. They also fly as far south as Brazil.
Photo by Johnslowry, August, Ontario.
It's possible for H. cresphontes to expand its range to places where oranges don't grow because, although they eat orange leaves, they can eat other things. We didn't always know that the caterpillars can survive a few frosts before pupating. Now we do. They can eat the leaves of rue, hops, prickly ash, and a garden plant sometimes called "gas plant." Naturalists reported finding them in Northern States in the nineteenth century, but in the twentieth century the population had retreated into Florida. It appears to be rebounding.
To believers in some theory of climate change, this looks like evidence. However, climate has not changed all that much. Orange trees aren't growing in Canada. In fact, the butterflies do not require Florida-type temperatures to survive, nor do they depend on orange trees, as we used to think. It seems more likely that a parasite, predator, or pathogen that wiped out the northern, prickly-ash-eating population has ceased (for the moment) to prevent this population from reappearing. The northern population may disappear as quickly as it appeared--even if the greedheads build data centers that cause serious local warming.
In Florida Heraclides cresphontes flies all year, but it is consistently most abundant in August.
Male wingspans are usually 4 to 5 inches; females' are usually 4.5 to 6". The record is 7.4". Wing markings are usually similar for both, with some differences from thoas that seem to be consistent but not conspicuous.
Along the southern tier of the United States this species has four generations a year, a generation lasting about 67 days. Wikipedia still affirms the old belief that they are only capable of "overwintering" in Florida or at least the Deep South, but we now know that they adapt into the pennsylvanicus form: Further north they adapt to a four-seasons climate, pupating after a few frosty days and eclosing in spring. Adaptation includes that northern caterpillars grow to a smaller size, and butterflies are likely to be at the small end of their size range too. Giant Swallowtails who have always lived in the North are not necessarily bigger than Monarchs or Tiger Swallowtails, after all. They can still mate with true Giants; their offspring could develop as true Giants if taken back to Florida.
This Massachusetts caterpillar has molted through four previous caterpillar skins and is ready to pupate at just two inches long. Photo from UMass.edu.
Heraclides cresphontes is found at elevations from sea level to almost 4,000'.
Photo by J-Stauffer, August, Florida. Like the
Atrophaneuras, these big Swallowtails can move their fore and hind wings separately. They fly somewhat slowly, with pauses between wing beats, but strongly.
Unlike many Swallowtails, males of this species tend to fly into the woods looking for females. Females spend most of their lives looking for host plants for their eggs, like other Swallowtails. In nature their preferred trees grew in forests, but they'll fly through open country and lay eggs on garden plants too. Populations can become established wherever they find enough host plants to start a colony.
They are pollinators. Favorite flower species include
"
Schinus terebinthifolius, Bouggainvillea glabra, Bourreria ovate, Carica papaya,
Eupatorium odoratum, Lantana involucrate, Metopium toxiferum, Morinda royoc,
Pithecellobium keyense, Lantana camara, Senecio mexicana and perhaps Delonix regia
"
...in Florida. (Quote from Delano Lewis.) In New England, they like
"
purple coneflower (Echinacea purpurea), butterfly weed (Asclepias tuberosa), common and swamp milkweeds (Asclepias syriaca and A. incarnata), joe pye weed (Eutrochium spp.), blackeyed Susan (Rudbeckia hirta), blazing star (Liatris spicata), and summer phlox (Phlox paniculata). Non-natives like butterfly bush (Buddleja davidii), zinnia (Zinnia elegans), and Mexican sunflower (Tithonia rotundifolia) will also attract the adult butterflies.
"
(Quote from UMass.edu.) They are also known to like milkweed and azalea flowers. They may sip at almost any flower once.
Males do, however, do some composting. Here an Eastern Giant Swallowtail joins Eastern Tiger Swallowtails sipping brackish water off a dead animal.
Photo by Richard Orr, Maryland, in May.
At the Reiman Gardens, Heraclides cresphontes also roosted together in same-species groups at night.
Photo by Bill Bouton, Arkansas.
Photo by SpecialMoth9897, May, Florida.
The female in a couple is usually bigger, but the most reliable way to identify females is that they lay eggs. If you have a clear photo of the underside, though, or don't mind handling the animals, Giant Swallowtails are big enough that it's possible to see whether an individual has retained "clasper" appendages at his tail end (male) or not (female). With a magnifying glass it's possible to see these features on smaller butterflies too.
Photo by Jeffrey S. Pippen, North Carolina.
Eggs can be more than a millimeter in diameter, and, although the female butterfly usually tries to place one egg on one leaf, she may place several eggs on a leaf if not sure where to find other host plants--so this species annot be foiled simply by planting other trees in between the orange trees. Eggs are whitish when freshly laid, reddish when about to hatch.
Photo from the University of Florida's FFL Gardens. Eggs and caterpillars are most often found on the top sides of leaves, though not always.
Hatchlings eat the shells from which they emerged. Even before they've done that they seem ready to go into their "Back off or I'll stink at you" display.
Photo by SoCalButterflies (which means it might have been
H. rumiko).
Caterpillars can be over three inches long,, and have long, bright red osmeteria. Their nickname is "Orange Dogs." They can be a nuisance, occasionally even a pest, in orange groves. Warts and markings between the head and the hump can look like tiny faces; the caterpillars are variable and their "face" markings can be quite amusing--or alarming, depending on your point of view. They can look like miniature snakes, dogs, lizards, even alligators. Some individuals have "face" markings on their tail ends as well.
Photo from Enciclovida.mx showing that in addition to the typical Swallowtail humpback, the caterpillars can have wide knob-shaped end segments. Or not.
Caterpillar on hops leaf in Ontario. Photo by N. Zitani.
Photo by Mark Eanes, August, Maryland.
Photo by Kent McFarland, Vermont.
Photo by Dorian Atchison, April, Florida, when the caterpillar appeared to be aggressively defoliating a small lemon tree. (It was feeling aggressive all right! Note the fully extended osmeterium. This species seem to display their osmeteria freely. The odor is described as sour, pungent, foul, unpleasant, detestable, and like a stinky cat litter box, though recognizably derived from citrus oil.) The trees usually survive their depredations. If stripped in spring, they still bear fruit next winter.
Photo by Christopherswan, September, Ohio. Not related to the horned-devils, this Orange Dog probably wouldn't mind being mistaken for a horned-devil. However, his "horns" subside back into his neck in a few seconds, and none of his little bumps and warts has even a bristle. People who don't mind the odor have been known to stroke and handle these caterpillars. (The caterpillars probably hate that.) Several of his bumps are paired and might look like eyes to a predator, but he's presenting the back of his neck and what is probably as close as a caterpillar can get to shoulders. The face faces down, jaws parallel with legs, directed toward a caterpillar's main interest--food. Caterpillars get no rewards for being pretty or nice. The most repulsive survive.
Photo by Andrew D. Warren, Florida. Siblings don't seem to harm each other in the wild, but here we see them warning each other off their feeding space. At GBIF.org there is also a disturbing picture of caterpillars of different ages left without food in a container, in which the two biggest caterpillars are trampling on the three smallest and threatening the middle-sized one. This species does not seem to develop the instinct to seek safety in numbers before pupation. It's easy to leave captive caterpillars without food, since fifth instar caterpillars eat so much, but it is cruel...especially when they may smell traces of chewed-up food inside a younger cousin. The SoCalButterflies post above confirms that caterpillars who are over an inch long are likely to eat smaller ones,though again that might be more true of
rumiko than of
cresphontes.
It is possible that Orange Dogs are considered pests, not so much because they reduce the orange harvest (they can, but not all that much) as because they are disgusting to orange harvesters. Like Zebra Swallowtails, they will rub their osmeteria against anyone perceived as an attacker and may spit to raise the squick factor even higher.
People who really hate these caterpillars--admittedly the caterpillars make that easy--have sprayed chemicals on them, with the usual results. Bacillus thuringiensis can kill the caterpillars, painfully, when they are young enough; it's cruel to watch. Methionine, an amino acid thought to be an essential nutrient for humans in its natural form, is being synthesized and tested for toxicity on Orange Dogs. As a guess that will work as well as other attempts to poison the little beasts have done. Most people like the butterflies. If humans think they have too many, they probably have too many. Simple predation is actually good for overpopulated butterflies. No caterpillar has ever evolved resistance to tongs or shears.
But some people, like this Brazilian butterfly fancier, actually keep the caterpillars as pets. The video has captions and some spoken content in Brazilian Portuguese. The captions say that the caterpillar called Poop grew up to be handsome--or pretty--whichever. I'm guessing "handsome" because, as a butterfly, he "adored" his human's face and hand. Male Swallowtails like human sweat and need to drink mineral salts in liquids so that they can mate; females need only find a mate to start offloading eggs. A male would be more likely to stay close to a known source of salty liquid for a few days, a female to flit away as soon as she could.
This is a longer, more sciency video, produced in the US. Nice scenery and fun facts if you want to watch a 45-minute video.
Pupae are about two inches long, grey and tan, camouflaged as short thick sticks.
Photo by Miscelaineous, May, Texas.
