Fall Webworm

What Are Fall Webworms? 

What causes thick webbing on trees?  

Is it bagworms, or tent caterpillars or some type of spider? No, it’s most likely fall webworms. The caterpillars produce a web of fine silk over the terminal ends of plants. They only feed inside the silken web, which they enlarge as they grow. The webs may become messy and not liked for aesthetic reasons, but usually don’t affect plant growth. The dry webs may hang in plants into the winter months. 

When do webworms appear?  

The first generation starts in May, which is usually small and goes unnoticed. They are normally on the south side of plants and form webbing over the terminal ends of branches. Look again from August through October for the second generation, which may be large and much more noticeable. 

What do webworms look like?  

The adult fall webworm is a small moth with white or possibly black wings. The larvae or caterpillar do most of the plant damage. Mature caterpillars are about one inch long and may appear in two color forms: those with black heads and yellowish white bodies and those with red heads and brown bodies. They are covered with long silky gray hairs. 

What trees do webworms prefer?  

The fall webworm usually attacks trees. There are over 100 species of deciduous forest and shade trees that may be attacked by this native moth caterpillar. However, some of its preferred hosts are sweet gum, willow, oak, linden, river birches, some maples, fruit trees and sometimes hollies.  

How do I get rid of webworms?  

There are a few ways to control fall webworms. Pruning out webbed terminals when monitoring your plants is one. Hand or poke pruners are useful with this method. The ’10 year old child’ method is another. Take a stick and use it to pull the webbing out and place in a soapy bucket of water for a few hours. This only partially gets the caterpillars out of the plants.  The last way is just to let Mother Nature take its course. Whichever method you use, allow Virginia Green Lawn Care to help you diagnose your pest problems with our Tree and Shrub Program!