Unraveling the mystery of webworm tents

fall webworms

Driving home from my youngest son’s soccer game, I was not prepared for the onslaught of questions fired at me. He had noticed the dense webbing on the ends of tree branches that formed a canopy over the country road. At first, I answered quickly talking about how they were made by caterpillars which would later turn into moths. 

Later, however, I had some explaining to do. 

It turns out that sometimes even moms are wrong. I had incorrectly identified the autumn web makers. I had called them tent worms. I had assumed that the same tent worms were around in the spring and the fall. With my limited knowledge of the subject matter, I struggled to answer many questions. 

Danielle LaPorte is quoted as saying, “If knowledge is power, then curiosity is the muscle.” Since I had one red X on my record and was riding the struggle bus of caterpillar knowledge, I had to do some research. 

Three types

Three native species are common in Ohio: fall webworms, eastern tent caterpillars and forest tent caterpillars. What I thought were eastern tent caterpillar webs were actually made by fall webworms. Other than the season, there are some other differences. 

Eastern tent caterpillars are usually found in the spring on fruit trees like apple, crabapple, cherry, chokecherry and plum. Fall webworms are not nearly as picky. 

In the fall, they can be found on more than 120 species of deciduous trees. They might even be on some of the same trees that eastern tent caterpillars were on in the spring. 

The location of the webbing on a tree is another way fall webworms and tent caterpillars are different. The eastern tent caterpillar spends the winter as an egg. The eggs look like a 3/4″ varnished ring-like mass on small twigs of the tree. 

The eggs hatch when leaves first begin to appear in the spring. The first thing the small caterpillars do is build a tent on a nearby branch fork in the tree. The tent becomes a temporary haven. The larvae leave the tent to feed on young foliage and then return to rest. 

Later in its life cycle, the insect forms white cocoons on tree trunks or other stationary items. Emerging in late June or July, the moths are mainly reddish-brown with two white stripes on each wing. The life cycle is complete and there is only one generation per year. 

Instead of building a tent on a fork of two branches, fall webworms always build their nests on the ends of branches. Typically, there is more than one generation in a year. The caterpillars spend the winter as pupae in cocoons hidden in the bark of trees or under the soil in the ground. 

Emerging by late April, the moths are white with brown spots on the wings. The female moths lay egg masses of 200-500 eggs on the underside of leaves. The newly emerged webworms encase the tips of branches with their webbing and consume the leaves inside the tent. 

After feeding in late spring and early summer, the first generation pupates in the soil. The second generation, seen in August and September, often expands existing tents, causing more defoliation than the first generation. 

Tackling tents

My husband shared a story about his grandpa trying to tackle webworm tents in an unusual way. His grandpa didn’t like the unsightly tents on his black walnut trees. He speared a corn cob onto the end of a stick, wrapped it with a rag that had been soaked with turpentine, and then lit it on fire. Then, he incinerated the offending webworms with his blazing weapon. 

Surprisingly, other than being ugly, the webbed tents created by fall webworms and eastern tent caterpillars are not harmful to trees. Other than young saplings, most trees can withstand the defoliation caused. 

It is significant to note that gypsy moths do not build webs or tents in trees. Gypsy moths are an entirely different story than fall webworms and eastern tent caterpillars. They are invasive and can destroy forests. 

Some people might think that the webs take away from strikingly beautiful fall foliage. However, it is just another reminder of the cycle of life and interdependency of nature. Endless questions about webbing on trees led us down the road towards knowledge. 

It also led us to snacks. I was hopeful that food would slow the interrogating barrage of questions.


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Julie Geiss lives with her husband and four children in Unity Township, Ohio. Faith and family are first in her life, but she also loves hiking, biking and camping. You can contact Julie at juliegeiss1414@gmail.com.



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