Fall webworm makes big webs, causes little worry

by | Sep 13, 2017

With scarf and pumpkin spice latte season right around the corner, enjoying the outdoors in the cooling weather is becoming more pleasant.  It’s also a more pleasant season for the fall webworm, who’s growing appetite is becoming more apparent.

Called the fall webworm because most of its activity is seen in the fall, these critters have actually been around most of the summer.  They have several generations throughout the year which build up until they reach their most noticeable population levels in the fall months.

Fall webworms are notorious for the webs they make at the ends of tree branches. They are usually quite obvious and many consider them unattractive, especially when they infest a landscape tree.  We may have a different opinion if it were October, when these webs could save us the trouble of hanging Halloween decorations!

The fall webworm makes eye-catching webs, but is typically not a cause for alarm. Image: R. Billings, Texas A&M Forest Service, Bugwood.org.

Fall webworm caterpillars eat tree leaves within the nest they create, causing localized loss of leaves. They feed on many species of hardwood trees, such as sourwood, pecan, hickory, walnut, maples, persimmon, and more.

As the caterpillars grow, the web expands, encompassing more and more leaves needed for food. They live in groups, so in a single web, there are many caterpillars. A closer inspection of the web will reveal excrement and shed skins of the caterpillars all left within their nest home.

Keep sipping your pumpkin spice latte though, as it is generally recommended not to worry about these web makers. Even when there are many nests of a single tree and it is nearly entirely defoliated, trees typically leaf out the following year and there is little long-term impact on tree health. In severe cases or when trees are defoliated year after year, the best management method is to remove the nests and destroy them.

So, enjoy the impending arrival of hot beverages and cooler weather and don’t sweat the growing webs. They’ll be gone soon enough.