Morbid Moth Meals: Variation at Work

National Geographic News recently stated that a species of Russian moth with a thirst for human blood demonstrates “evolution at work.”1 The moth, Calyptra thalictri, was filmed boring into a researcher’s thumb, evidently to draw a blood meal.

Entomologist Jennifer Zaspel at the University of Florida in Gainesville told National Geographic, “We see a progression from nectar feeding and licking or lapping at fruit juices to different kinds of piercing behaviors of fruits and then finally culminating in this skin piercing and blood-feeding.”

However, it seems unlikely that this is “a fruit-eating moth evolving blood-feeding behavior,”1 since blood-sucking moths are not new.2 A different species of Calyptra in Malaysia can puncture the skin of a tapir, a three-toed animal that resembles a swine. The mouthparts of the moth are so designed that they can be used to obtain nourishment from either fruit juices or blood. Zaspel speculated “that this represents something different, something new.” But there are no new structures or new biological information—just a new source of food. This phenomenon does not explain the origin of the mouth structures that moths use to eat, it just indicates a change in feeding habits.

Rather than demonstrating descent-with-modification (macroevolution), the moth behavior more likely involves a preferential shift from one food source to another within the same species of animal. Such a shift makes sense within the biblical creation model, which holds that even the animal world has been affected by the universal curse placed on creation because of man’s sin.3 From a creation perspective, the moth mouthparts were originally designed to pierce fruit. A switch to a blood diet doesn’t demonstrate macroevolution, but instead an originally good design now misplaced and redirected due to environmental forces.

There are moths that use their proboscis to drink tears from bantengs (in Thailand) and other species that feed from the tears of birds. Likewise, the hook-and-barb-lined tongues of Calyptra thalictri can be used to feed on blood as well as fruit. Skeptics of neo-Darwinism ask for real evidence for Lepidoptera evolution—perhaps a transitional mouthpart from the “ordinary” curled moth proboscis to the hook-and-barb-tongues of the vampire moth.

References

  1. Roach, J. Vampire Moth Discovered—Evolution at Work. National Geographic News. Posted on nationalgeographic.com October 27, 2008.
  2. Banziger, J. 1980. Skin-piercing blood-sucking moths III: Feeding act and piercing mechanism of Calyptra eustrigata. Mitteilungen der Schweizerischen Entomologischen Gesellschaft 53:127-142.
  3. Romans 8:22.

Photo © Entomart

* Mr. Sherwin is Senior Science Lecturer.

Article posted on November 6, 2008.

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