Consult the label for dosage rates and safety precautions. Birch skeletonizer, Bucculatrix canadensisella . This insect has periods of great abundance about every 11 years when it defoliates white birch trees in the northern states. There is one generation each year. The larvae complete feeding the latter part of September and spin cocoons under fallen leaves and other debris on the ground where they pass the winter.
Birches injured are the gray birch, white birch, yellow birch, and European birch.
Spraying with malathion, which is among the compounds registered for control of this pest in Connecticut, about the middle of August will protect the trees against injury. An alternative to foliar sprays is to apply imidacloprid as a systemic to be taken up by the roots, which provides season-long control. Consult the label for dosage rates and safety precautions. Bronze birch borer, Agrilus anxius . This insect is the most destructive, of all birch insect pests occurring in Connecticut, to the European white birch and its cutleaf variety.