Vampire Moths Suck the Blood of Vertebrates, Including Humans
By Kevin Fitzgerald
Vampirism — piercing or cutting animal skin to suck or lap up blood — is known throughout the animal kingdom. Mosquitoes come to mind, plus ticks, mites, vampire bats, and the vampire finch of the Galapagos Islands. But … vampire moths? Yes indeed, there are moths that feed on the blood of vertebrates, including humans. When I tell people about them, they respond by going into mild shock. Like carnivorous plants, nothing so strange should exist in a prosaic universe, they say. But who ever said we live in a prosaic universe?
The vampire moths belong to the genus Calyptra, which contains 17 species. The genus is contained within the subfamily Calpinae of the family Erebidae. The genus is also a member of the Calpini tribe. Eight species have been reported vampirizing mammals, including humans, in the wild, and two, Calyptra fletcheri and C. thalictri, have drawn human blood in laboratory or semi-natural settings such as mesh cages and vials. All of them, including the blood-drinkers, feed normally by piercing fruit to suck the juice. Blood-drinking in these creatures is facultative, not obligate.
Vampire moths are being studied extensively in the laboratory of Dr. Jennifer Zaspel, assistant professor of entomology at Purdue University in West Lafayette, IN. Her team has captured Calyptra moths in the field in the U.S. and other countries. The lab studies, among other aspects, the molecular systematics and feeding structure of vampire moths. Dr. Zaspel is also director of the Purdue Entomological Research Collection, which contains nearly two million insect specimens.
All Calyptra species are found in the Old World (southeast Asia, eastern Africa, China, Japan, India, and eastern and southern Europe) except Calyptra canadensis, which lives in the U.S. and Canada, and is probably not a vampire. But who knows? Maybe it just hasn’t been caught in the act yet. The life history of C. canadensis was almost unknown until recently, when, in Zaspel’s lab, one of them was videotaped piercing a strawberry.
Vampire moths can pierce the thick hides of animals such as buffalo, tapirs, and elephants. After landing on a favorable spot on the host animal, the moth begins penetrating the skin by applying its proboscis to the skin, then rocking it back and forth to push it in. Having penetrated the skin, the moth then oscillates, or rocks its head back and forth, to drive the proboscis further in. As blood from the host animal wells up, it opens hooks on the sides of the proboscis to anchor it firmly. The proboscis has two parts that alternate between anchoring and drilling through host tissue using an “antiparalell” movement. A bite from a Calyptra moth is red and sore, but is believed to pose no danger to human beings. A vampire moth can suck blood for up to 50 minutes.
In 2006, Dr. Zaspel herself was vampirized on a collection trip abroad.
“My first encounter with a vampire moth was as a graduate student working in Far Eastern Russia,” she said. “We went out collecting in a remote village outside of Ussuriysk and one of the first moths that came to the sheet was Calyptra thalictri. I knew blood-feeding had never been documented in this species, but still, I decided to collect it into a vial and stuck my thumb inside. In less than one minute, it began probing my thumb with its armored tongue, and then it pierced through my skin, and began feeding on my blood.”
Only the male vampire moths suck blood. The females suck fruit juice and feed on nectar, and the larvae feed on leaves. It is hypothesized, though not proven, that males suck blood for the salt, which they then pass on to the females in their sperm as a possible benefit to the offspring. It is also hypothesized that the blood-feeding behavior evolved from piercing fruit in order to feed on juices.
“Male and female Calyptra species are obligate fruit piercers,” said Dr. Zaspel. “They have a proboscis that is modified for piercing fruits and sucking the juice. Thus, the blood-feeding habit has evolved from plant-associated feeding behaviors, as opposed to animal associated feeding behaviors.”
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Kevin Fitzgerald is a freelance science writer living in Connecticut. He has published in newspapers, encyclopedias, and online.