Beetles deterred by pheromone packets

By Erin McIntyre

These aren’t the trees you’re looking for.
That’s the message sent by the scent wafting from the Douglas Fir trees on Ouray’s perimeter.
The smell emanates from bubble packs stapled to the trees, which contain chemicals manufactured to mimic the pheromones pine beetles use to send messages to each other. This time, the message is they should keep on truckin’. Like a Jedi mind trick delivered by Obi-Wan Kenobi, this pungent mixture smelling of tires and syrup fools the tiny, pin-sized insects into thinking these trees are already taken. They’re dying and there’s nothing to see here.
On Tuesday morning, volunteers Shawn Kitchens and Aaron Silverman of Ouray and Robert Gaspari of Ridgway joined Colorado State Forest Service Forester Austin Shelby and Supervisory Forester Jodi Rist to hang the pungent ornaments on the trees. Their goal is to apply 700 packets to Douglas Fir trees, to cover the area and send the message to the beetles that there’s no vacancy.
The chemical, MCH, is an anti-aggregate pheromone, a chemical developed to mimic the beetles’ pheromones. The MCH sends the same message that their bodies do in nature: This tree is taken. Move on. It deters other beetles from congregating at that tree, fooling them into thinking it’s already claimed by beetles who got there first. While some pheromones attract insects to gather, this one sends the opposite message.

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