A previously unknown population of vampire moths has been found in Siberia. And in a twist worthy of a Halloween horror movie, entomologists say the bloodsuckers may have evolved from a purely fruit-eating species.

Only slight variations in wing patterns distinguish the Russian population from a widely distributed moth species, Calyptra thalictri, in central and southern Europe known to feed only on fruit.

When the Russian moths were experimentally offered human hands this summer, the insects drilled their hook-and-barb-lined tongues under the skin and sucked blood.

Entomologist Jennifer Zaspel at the University of Florida in Gainesville said the discovery suggests the moth population could be on an "evolutionary trajectory" away from other C. thalictri populations. This is the second population of vampire moths Zaspel and her team have found. They discovered the first in Russia in 2006.

Next January, she will compare the Russian population's DNA to that of other populations and other species to confirm her suspicions.

"Based on geography, based on behavior, and based on a phenotypic variation we saw in the wing pattern, we can speculate that this represents something different, something new," Zaspel said.

"But it is really difficult to say without knowing genetic differences between individuals in that population, and among individuals from other populations, how different this group is going to be."

Blood Feeding

If it turns out that Zaspel has indeed caught a fruit-eating moth evolving blood-feeding behavior, it could provide clues as to how some moths develop a taste for blood.