By Bruce Finley
Colorado is deploying tiny predator wasps imported from China — 200 a week through mid-July — in a state experiment aimed at annihilating invasive beetles threatening one in six metro Denver trees.
The Oobius agrili wasps target eggs of emerald ash borer beetles, also from Asia, which have killed more than 50 million trees in 25 states and spread across 12 square miles within Boulder.
Wielding ovipositor points on their bellies, these wasps can pierce beetle eggs and lay their own eggs inside. Oobius larvae then devour beetle eggs, defeating borer beetles by preventing population growth.
"This is an experiment. We hope it is enough and that the wasps will establish themselves. The idea is they will reproduce on their own," said John Kaltenbach, biological control specialist for the state Department of Agriculture.
But instigating bug-on-bug war to save an estimated 1.45 million metro Denver ash trees depends on keeping the wasps comfortable — and strong enough to make it through winter.