They're at it again! The Bird Cherry ermines! I talked about this on the 4th of June last year, but I think it's worth another comment. The Bird Cherries (prunus padus) on mid Speyside are suffering what appears this time to be an extreme Ermiine Moth infestation. The ‘cobwebs’ you can see on many trees along the Speyside Way are not the work of an invasion of giant spiders, only the result of activity by a relatively common moth, the Bird Cherry Ermine (Yponomeuta evonymella)
On hatching, the caterpillars of this moth can quite quickly spin a silk ‘tent’ over the twigs and branches where they can feed on the leaves in safety, protected from birds and parasitic ichneumon wasps by their surrounding shield.
During a major infestation of ermine moth caterpillars, whole bird cherry trees can be completely enveloped in this silken stocking and become totally defoliated. These outbreaks are sporadic, however, and while the trees may appear leafless and lifeless immediately afterwards, they tend to recover in subsequent years.
This year, however, many trees are also weakened by snow damage with many broken and cracked branches. It remains to be seen what the outcome will be.
