There are no truly pink butterflies. There are just a few pink moths. Hemileuca hualapai, the Hualapai Buck Moth, flies in the daytime and can be mistaken for a pink butterfly. Actually it has a reddish body and thinly scaled, white or transparent wings. The edge of the forewings is yellow, and there can be a yellow spot in the middle of the wing.
Photo by Jimeckert49.
Sometimes pink spreads along its wing veins--the color coming from the moth's chitin; its blood, or haemolymph, is clear.
Photo by Jmbearce. This one seems to be just emerging from pupation, crawling up through loose soil, spreading her wings as she goes. Newly eclosed Hemileucas look like grubs. At this stage their genders are obvious: females are egg-stuffed, males look skinny. Neither sex carries much fat; when the eggs have been laid females look thin too.
For "giant silk moths" they're small. Some people think they're cute. The wingspan is usually between two and three inches but the moths often fold their wings and try to look like smaller, harmless species.
Photo by Pierre Martin.
The moths are found in southern Arizona and northern Mexico, wherever they find dry grassland as distinct from desert. Most of these photos came from Mexican sites although the photos were reportedly snapped in Arizona and web links, when provided, were in English. Most other clear photos of H. hualapai online were at Bugguide.net, which is managed by Real Entomologists but identifies specimens from photos alone.
There's a dismissive quality in the online literature about this species. They're not as big or as showy as some other Hemileucas, so to some people they're less interesting. They look a bit like the White Tiger moths we have on the East Coast, but are bigger and less pleasant to know--White Tiger caterpillars are furry but don't sting. Apart from that little disappointment I think hualapai's main image problem is that they don't live in California. The caterpillars seem about as nasty as other stingingworms; the moths are about as pretty and as empathy-worthy as other Hemileucas. People seem, however, to have photographed them more than formally studied them. More photos have been posted to nature sites asking for a species identification than have been posted in reports about studying or cage-rearing the animals. And a few people have offered close-up photos of this moth's wings as wall art, or pictures of the moths as bumper stickers.
Nevertheless, a few academic studies have been done:
One interesting study, more relevant to the more "gigantic" silk moths, determined that the fancier wing tips of moths in genera like Actias helps to blur their sonar profiles and make them harder for bats to locate, relative to plainer-shaped, smaller moths like the Hemileucas.
One source mentions that another genus name was proposed for this species in the nineteenth century. They're not hemi leuca--half white. One naturalist wanted to call this white moth Euleucophaeus, Good White with a Dark Shadow. Leucophaeus was in use as a name for a kind of seagull, and perhaps this naturalist thought that moths were nicer animals than seagulls? Anyway that name's not really accurate either, so the consensus of scientific opinion has been to classify this moth as a Hemileuca.
This European, for whom Hemileuca hualapai is exotic and rearing one has been a triumph, captured an interesting fact about hualapai while bewailing the fact that his film set-up doesn't capture its pink-white color. Something under that smooth, even, pale pink surface gives the moth the standard Hemileuca color bands--even if human eyes don't see them in natural light!
Adult hualapai fly in April and May. They neither eat nor drink, but live entirely on that body fat of which they have stored so little. Giant silk moths can live for a week after eclosion but, realistically, most live for one or two days.
First this young moth stretched her legs, climbing up and away from her pupal shell. Then she stretched her wings. Then, immediately after or even during the unfolding of her wings, she started stretching and twitching her tail segment. The tail tail end of a moth is generally called the abdomen but. during pupation, the moth literally digested and excreted its digestive system; the abdominal segments are now used for reproduction only. The moth has reached the stage of gestation where her eggs need to be fertilized, and the twitching behavior pumps out a scent that humans don't recognize, summoning male moths from all over the neighborhood. It may take an hour or two for prospective caterpillar-daddies to arrive, after which the couple spend a half-hour or an hour together, and the female spends up to another half-hour flitting around, apparently just to enjoy the use of her wings even if a suitable host plant is nearby.
After those few hours, she may spend the entire rest of her short life laying eggs. She has no real defense against predators and little stored-up energy. If she survives after laying her first and biggest batch of eggs, she'll be "old" in moth society, less interesting to males. Nevertheless, many female Hemileucas lay two or three batches of eggs. Later broods will be less fertile whether or not they are freshly fertilized by a second or third mating, which the moth will do if possible. The rate of reproductive success declines steadily as the moth ages through her last days--if she has days to live as an adult moth. Still, some eggs from second and third broods do hatch. The odds are always against any moth egg ever becoming an adult moth next year, yet a few of them always do.
Moths find mates as quickly as possible, then lay eggs on grass stems. Caterpillars will hatch in July or August and eat grass.
When a genus of moths or butterflies is described, species descriptions often identify exceptions to the rules of the way the genus generally look and behave. Swallowtail butterflies have little tails on their hind wings, except for some species that don't. Tiger moths are generally about one inch long with a two-inch wingspan, except for Giant Leopard Moths, which are almost twice the size. Wouldn't it be pleasant if this series on the Hemileucas were to come to an exception to the rule that the caterpillars have sharp, stiff, venom-filled stinging hairs? Well, there's not one. If there were, hualapai wouldn't be it. Baby Hemileuca hualapai can look pink or purple, and they're one of the species of "stingingworms" whose bristles form rosettes with all the stinging hairs of about the same length, producing a more painful sting than the ones whose bristles form branches like little trees.
Young, small caterpillars are reddish. Like other Hemileucas, they stay in a cluster until they grow big enough that each one needs its own leaf to eat. Then they separate.
Photo by James Wolf.
The red color can be very striking in the older caterpillar.
Or they can look more like other Hemileucas:
Photo by Sambiologist.
While some caterpillars change colors with each molt, and Hemileuca hualapai are variable, this photo shows how their coloration depends more on diet and heredity than on age. With that underlying red color they can be a reddish gray that can even look purple, a reddish tan that can look orange, or a dull yellowy brown...and this individual's brand-new skin seems to be the same shade of brown that its old skin was.
Photo by Charles Melton.
By October they're ready to pupate. This is done by crawling under some sort of shelter, a few inches of loose sand or some such thing, and waiting for the last caterpillar skin to fall off. Then they spend the winter trying to look like pebbles, and if all goes well they climb up into the light and spread their wings next spring.
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