Full spotted moth infested north forests

Officers of the VNIILM center of biotechnologies in forest protection believe that it is untimely and baseless to refer mass full spotted moth infestation of trees in the Archangelskaya region over the last years to just climate change.This event needs comprehensive monitoring and study. .

Full spotted moth Yponomeuta evonymella is a small moth of silver colour with little spots scattered across its wings as if it put on a ermine mantle. The moth caterpillars damage bird cherry trees and this year such damage outbreaks have been identified in several rather far away from each other Russian regions.  .     

It is one of the common bird cherry phytophages that once and again is subject to mass reproduction. The damage for bird cherry is not deadly if it is a strong and healthy tree. Defoliation will affect it and next year bird cherry flowering and fruit yield won’t be so abundant as usually. Such damage is hazardous when caterpillars defoliate trees already affected by stem rots. In this case a tree loses its capacity of efficient resistance to these rot agents and it promotes their stronger evolution.   

There several representatives of this moth genus. All of them during mass reproduction wrap trees with cobweb. Sometimes when this a whole lot of caterpillars they destroy foliage completely wrapping defoliated branches with rather thick cobweb cover.

There are a lot of “but” in this pest control operations. In particular there is no its control in forests since full spotted moth damage only bird cherry and this tree species grows in river and creek bottomlands where pesticide application is banned.

Full spotted moth population outbreaks are quite often in urban communities. It is also difficult to kill the pest there – chemical preparation application is not allowed in populated areas. Caterpillar nest removal by cutting with its follow-up destruction gives a good result but it should be done when caterpillars are in its early ages and have not damaged severely. However at this time it is difficult to find its small nests. If whole crown is wrapped with cobweb nest cutting and destruction of caterpillars in them makes no sense in this case whole crown should be cut.. One cannot rely on insect eating birds since full spotted moth caterpillars live in cobweb that prevents access of birds. Application of bacterial preparations such as lepidocide is very efficient. But its applications should be done when there is a lot of foliage on a tree. If whole crown is defoliated protective treatments make no sense as well.