…now you don’t!
Chalcophora virginiensis (Drury, 1770) is the largest jewel beetle (family Buprestidae) in eastern North America. This beetle is also known as the “sculptured pine borer”, and its easy to see why—its hyper-sculptured, shiny metallic body glitters like a jewel in the sunlight! This feature is typical of many species in the family and, in fact, is the source of the family’s other common name—metallic wood boring beetles.
Such dramatic sculpturing and coloration makes cabinets of jewel beetle specimens among the most beautiful in any museum, and for those who have only seen these beetles as pinned specimens in cabinets it can be hard to imagine what purpose such appearance serves. In its native habitat, however, on native host plants, the reason becomes clear. Rather than conspicuous and easily seen, such coloration actually helps the beetle to blend in with its environment and become almost invisible. Measuring well over an inch in length and possessing no other way of defending itself by biting, stinging, or even just tasting bad, these beetles would be a more than healthy snack for almost any avian or reptilian predator, and going about their activities during the day right under the noses of all these visually based predators makes finding mates and oviposition sites an even riskier proposition. For them, the best way to beat a visual predator is to become… invisible! The two photos above show just how dramatic a difference the substrate plays in allowing these beetles to practice their disappearing act. Land on the trunk of a dead or dying pine tree, its aged bark flaked and graying, and the sculpturing and coloration are a perfect match. Land, however, on a healthy tree, its resin-filled bark bright and full of color, and it suddenly becomes a sitting duck. It’s in the beetle’s best interest to be good at telling the difference between thrifty and unhealthy trees, which they do by “smelling” volatile chemicals emitted by trees under stress.
Those interested in more information on this species and its close relatives may wish to consult the recent review of the genus in North America by Maier & Ivie (2014) (see my review of this excellent paper here).
Maier, C. A. & M. A. Ivie. 2013. Reevaluation of Chalcophora angulicollis (LeConte) and Chalcophora virginiensis (Drury) with a review and key to the North American species of Chalcophora Dejean (Coleoptera: Buprestidae). The Coleopterists Bulletin 67(4):457–469 [abstract].
© Ted C. MacRae 2015