Browntail Moth August Update 1
Browntail Moth August Update 2

The new generation of Browntail moth (BTM) egg masses hatched during the week of August 7. 

Newly hatched caterpillars are pale yellow, with a black head and two dark spots near their head (see photo). 

Depending on the weather, these young caterpillars will communally feed on host plants from now until the end of September or the beginning of October. 

This time of year, damage is generally not a severe health issue for the trees. The BTM caterpillars will also start building their winter web for shelter through the coldest months. 

The young caterpillars feed on the leaf’s outer surface, the epidermis, without consuming the entire leaf. If your tree is micro-injected with Arborjet® TREE-äge R10, caterpillars coming to your trees are also consuming this effective treatment. 

This damage is called skeletonization and causes the leaf to die and turn a copper color. Some skeletonization damage is visible from the ground. In these trees, leaves on the outer tips of the branches are a copper hue. 

Although it is much less common this time of year, exposure to hairs from previous seasons’ caterpillars can still cause skin irritation. These exposures often happen during activities that stir up hairs in the environment during dry conditions, such as yard work. Caterpillar hair exposure can also occur through contact with old pupal cocoons, which are often still attached to host foliage / sheltered areas, or surfaces on which hairs settled that have not been washed clean. The caterpillars now feeding on the leaves are unlikely to cause a reaction in most people as this new generation’s hairs are not toxic. 

For several reasons, treatment this time of year of the Browntail caterpillars can be successfully treated through microinjection of Arborjet® TREE-äge R10:
  • The need to detect feeding caterpillars is eliminated as Arborjet® TREE-äge R10 is present within the leaf

  • Caterpillars in late summer are not necessarily found on the same trees they defoliated in the spring; Arborjet® TREE-äge R10 protects your trees from any caterpillar coming to your trees

  • Unlike other non-systemic pesticides sprayed on leaves, Arborjet® TREE-äge R10’s is an effective systemic as it is within vs. on the leaf.

  • Arborjet® TREE-äge R10’s unique 2-year ability is ideal for:
    • Late summer and fall Arborjet® TREE-äge R10 is effectively absorbed throughout the tree’s leaves, effective during late summer and fall feeding.

    • During the winter, the caterpillars strip the epidermis while constructing their winter nests consuming Arborjet® TREE-äge R10.

    • In the spring, the new generation of caterpillars that emerge from their winter nests and start to feed, Arborjet® TREE-äge R10, is already there, protecting the emerging buds and leaves.