The emerald ash borer (Agrilus planipennis) is a beetle native to Asia which was first identified near Detroit, Michigan and Ontario in 2002. It is now a serious invasive pest of North American ash trees in the genus Fraxinus. Emerald ash borer populations are spreading rapidly in the Midwest and Mid-Atlantic states of the USA, as well as adjacent regions of Ontario, Canada. “Within 25 years, practically no ash trees may remain on either side of the St. Lawrence Seaway”, said Akhlesh Lakhtakia, Charles Godfray Binder Professor of Engineering Science and Mechanics at Pennsylvania State University.
Emerald ash borer adult males locate females using visual cues, and males can be attracted by using dead male or female beetles pinned to host trees. The beetles are in the family Buprestidae, also known as Jewel Beetles as they often have metallic, iridescent colouring. Thomas Baker, Professor of Entomology at Pennslyvania State University and Michael Domingue have previously used dead female emerald ash borers for bait to trap the male beetles. The dead emerald ash borers are not ideal for trapping due to their fragility, therefore two researchers working in Lakhtakia’s laboratory have created a decoy beetle made from a mold of the female beetles body. The decoy has been coloured using a process of layering polymers with different refractive light properties to create the characteristic iridescent green colouring of the emerald ash borer. The team were able to find the right combination of polymers and number of layers in order to refract light and create a colour very similar to the beetle’s own colouring, creating a realistic visual decoy.