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Fall Webworms: Friend or Foe?

Ok, I know the first thing you are thinking is “what the heck is a fall webworm?” Well, you’ve come to right place. We’re going to tell you everything you ever wanted to know about fall webworms and more. 

What Exactly is a Fall Webworm?

You walk outside one fine late summer/early fall morning, glance up to see if the leaves have begun changing and instead of vibrant reds, oranges and yellows, you see big large dense webs covering often every tree branch in sight. While they are definitely unattractive, and frankly, kind of dangerous looking, Dr. Steven Frank, a North Carolina State entomology professor says, “Unless you are a tree being infested by fall webworms…” they are nothing more than “a perennial nuisance.” Though if you are owner of an infested tree then Dr. Frank continues, “…and in some cases a destructive pest.” 

Technically a fall webworm web isn’t a true web like what a spider spins. It is a cocoon woven by the fall webworms so the females have a place to lay their eggs. These eggs attach to the bottom of the leaves and get their nourishment from the tree branch the cocoon covers. 

Fall Webworm Life Cycle 

The scientific name is Hyphantria cunea. The common name is Fall Webworm. But the funny thing is they are most active during the spring. The name comes from the fact that the fall season is when they become more noticeable as the cocoons expand as the eggs hatch and the caterpillars grow.  

During the colder months adult fall webworms hunker down in their winter cocoons. Then as soon as the days become warmer the females begin to lay their eggs. These eggs almost immediately begin to feed off the tree branch their web/cocoon is attached to. They do this continuously throughout the spring and summer. Toward the end of summer the caterpillars begin to emerge and the cocoons, now full of frass, or insect excrement, begin to break up. If you can reach them, you can remove them with a long handled rack. But frankly, why go to all the work? 

Are Fall Webworms Harmful?

As Dr. Frank said, only if you’re a tree. But that really isn’t even true. There is very little danger of long-term damage to a healthy well-developed tree. The biggest problem is simply the way the webs/cocoons look. Though problems may occur if the same tree is host to fall webworms over a period of many years and the tree becomes completely defoliated. Then if added stress of a drought or another type of pest infestation happens, branches may become distressed to the point where they begin to die off.  So bottom line, while fall webworms make a cool Halloween decoration, they are nothing to worry about. 

Now is the best time of the year to get your trees inspected and pruned before the cold weather and winter storms hit. Call Out on a Limb Tree Service today at 864-320-8787 to schedule an appointment. 

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