After the early spring green of May the poplar leaves in the valley have turned almost silver with the mottling of lacy caterpillar trails.
It’s an epidemic of the aspen serpentine leaf miner (phyllocnistis populiella), according to entomologist Ken White of the Ministry of Forests, Lands and Natural Resource Operations. And the infestation isn’t just here but is also in the Stewart-Cassiar and Cariboo regions as well.
“I’ve never seen it this bad,” said White, who has been here for 15 years.
White said that people are seeing in the leaves of poplars are the eating of trails by the tiny, flat caterpillars which feed just under the cuticle of the leaf. If one examines the leaf closely you can see that the trail starts off narrow and gets bigger as the caterpillar grows. The caterpillar started off as an egg laid on the leaf bud in early spring by the tiny whitish aspen serpentine leaf miner moth.
Although the leaf miner reduces a tree’s growth, White said direct mortality doesn’t normally happen because the tree still has some ability to photosynthesize. White also explained that aspens are very hardy and have lots of adaptations for survival, including “reflushing,” which is the ability to put out a second set of leaves.
Will the epidemic be with us next year?
White said the caterpillars have now finished mining the leaves and have turned into moths which do overwinter here, but what that means for the aspens next year is uncertain.
“There hasn’t been much study on this,” said White.
And this is also the reason that White can’t provide any explanation as to why the aspen serpentine leaf miner infestation is so bad in the Bulkley Valley and other areas of the province this year.
- by Rosmary McKenzie