Webworm Nests: Signs of Trouble?

In late summer or early fall, your trees may start showing signs of webworms.  Large webs or nests may form on branches, like a gigantic spider has taken over.  However, you are not being invaded by arachnids but rather the larva of white moths.
 
During the winter, the pupa form of this insect hides in the ground or in cracks in concrete or buildings.  During the summer, the now-adult moths will mate and lay eggs on the underside of leaves of deciduous trees.  After approximately one week, the caterpillars emerge and create the web-like nest while they feed on the leaves.  In the nests you can find hundreds of caterpillars, their droppings, and remnants of leaves.  Finally, they will leave the nest and spin a cocoon in the ground for the coming winter.
 
Despite the creepy appearance, webworms are basically harmless.  They do not cause damage to the tree and, in fact, only eat the surface of the leaves.  The remnants of the leaves will turn brown and stay in the nest.  The only real damage is cosmetic.  Any leaves killed by the caterpillars will grow back the following year.
 
While webworms don’t cause damage to adult trees, however, they can damage younger trees.  A tree in the first year or two of growth and development may not be able to handle the loss of foliage.  Therefore, the nest should be removed as soon as it is noticed in order to protect the young tree and ensure its overall health, growth, and development.
 
There are a few different ways to remove or kill webworms and their nests.  The simplest is to physically pull the webbing off using a shovel, rake or broom.  Of course, this can only work on small trees, and may create a mess as the nest comes down.  You can also prune the affected branch.  Any limbs that you cannot reach from the ground should be cut by a tree trimming professional.  Pruning should be carefully considered.  You will be removing limbs that would sprout healthy leaves next year.  Another option is to encourage birds and insects that kill webworms.  Of course, they may be a problem insect as well.  Pesticides such as Bt or Neem can be used, but any type of pesticide may kill other insects like butterflies.
 
For more information on webworm nests, or for advice on how to remove webworm nests safely, contact your local tree care professional today.  A tree trimming professional will be able to provide you additional information on webworm nests as well as even help you remove them and protect younger trees.