Insect Damage

• The introduction into the U.S. of various species of birch leaf miners occurred in the early 1900s. The birch leaf miner is closely related to bees, wasps and ants. The insect's creamy-white larvae feed heavily on the birch tree's foliage. The native bronze birch borer beetle's larvae burrow into the tree's wood. Once within the confines of the bark, the larvae feed on the tree's wood and develop a tunnel system. The larvae pupate into adult beetles, which then feed on the tree's foliage, mate and start the cycle of destruction again.
  
  

Life or Death

• An infestation of birch leaf miners will not kill the birch tree, but it will render it unsightly. The bronze birch tree borer will kill the tree if control does not occur. If more than 50 percent of the tree's crown shows death from an infestation of birch tree borers, the tree will usually perish, according to the U.S. Forest Service's website. The tree may take several years to show such extensive damage, or it may occur in only 1 year.
  
  

Birch Leaf Miner Control

• Control birch leaf with systemic, foliar or paint-on insecticides. Spray the tree's foliage within two to five days of the first noticeable leaf yellowing in the spring. Consider reapplying foliar sprays in July if necessary. Apply systemic soil insecticides before the tree's buds appear in the early spring. Consider painting the trunk with a paint-on insecticide in the spring, as the tree's foliage emerges and grows. Water the tree regularly and maintain an adequate fertilizer regimen to help the tree remain healthy. A healthy tree quickly recovers from defoliation the insects cause.
  
  

Bronze Birch Borer Control

• Consider planting bronze birch borer-resistant birch tree varieties, such as the Heritage birch (Betula nigra Heritage) or the red birch (Betula nigra), which provide resistance to the bronze birch borer. Maintain the tree's overall health, so it naturally fights off the insects. If an infestation does occur, deeply saturate the birch tree. Water the tree slowly thoroughly for up to three hours to a soil depth of 18 inches per week. During the spring and summer months, apply three applications of bronze birch borer insecticides to the tree's bark. The insecticide does not reach the insects deep within the tree's wood but prevents new pests from burrowing into the tree. Prune any dead branches and immediately discard them.