September 04, 2010

Outdoor Hour Nature Studies - Webworms

outdoor hour button We’ve begun the Outdoor Hour Nature Studies.  Some time ago I posted about the resources I am using.

For today’s outdoor nature experience, we decided to explore The Nature Trail near our new home.  The weather was wonderful in the low 80’s and it was sunny with a nice breeze.  We couldn’t have ordered nicer weather.

We saw some really neat trees with curling leaves and some nice purple flowers.  But the most curious thing we encountered were these webs in some trees. 


I’ve seen these before as I was driving down the street and assumed that they were some sort of spider web.  I see web and I think spider, the two just seem to go together for me.

8681 However curiosity got the best of us, which is the point of course, and we had to get a closer look.  Mason did not want to look up close.  He associates webs with spiders too.  Upon closer examination, Mattie and I could see caterpillars in the web.  We didn’t notice any spiders, but there were tons of caterpillars.  Can you see them?

Through a quick internet search, we decided that these were either tent caterpillars or webworms.  Tent caterpillar webs seemed much denser than these, so I was leaning toward webworms and then I found this.

FALL WEBWORM (The Morton Arboretum website)

The fall webworm differs from the Eastern tent caterpillar by the time of year in which it is seen, its feeding habits, and the placement of its protective tent.
In its larval state, the webworm is a 1-inch caterpillar, usually pale yellowish-green with a broad, dusky stripe down its back and a yellow stripe on each side. They are covered with long, silky gray hairs that arise in tufts from orange yellow or black tubercles. The color of the head can be red to black. As an adult, the fall webworm emerges as a white moth with a wingspan of about 11/2 inches. Occasionally there are a few black or orange markings on the body and legs.


Adult fall webworms appear mostly from May to August and deposit egg masses of up to 1500 eggs on the lower surface of leaves of a host tree. As they hatch, larvae quickly begin spinning their webs over the leaves on which they feed. This web enlarges to cover more foliage as the larvae continue to feed. If a tree is heavily infested, it is possible to have several branches enclosed in webs. After feeding, the larvae drop to the ground to spin thin cocoons just beneath the soil surface where they will overwinter until the following spring, emerging as adult moths. Approximately 120 species of deciduous trees are host to the fall webworm, with mulberry, maple, crabapples, birch, chokecherry, walnut, and willow being most susceptible. The damage occurs in late July and August as the larvae feed on leaves while inside their tents. Immature larvae eat only the outer surfaces of the leaf and leave the leaf veins untouched, while mature larvae will consume the entire leaf right down to the petiole. Nevertheless, given the time of year that the feeding takes place, the fall webworm’s damage is more of a cosmetic problem to the tree than any serious health threat. If the fall webworm has infested a small tree or a recent transplant, some control measures may be warranted.

Now that we know more about the webworms.  We will be able to check on them through the fall and possibly witness their drop to the ground.


  1. We have these too and they are very interesting to watch. Thanks for sharing your link. :)

  2. We are getting geared up to join the Outdoor Hour too, waiting for our Handbook of Nature Study to arrive. We've seen those webs before and I, too, assume spiders. I'll have to show your post to my kids, they'll love it.

  3. We had tent caterpillars in one of our trees earlier this year. It was fun for the kids to have so may caterpillars around but we had to cut the branch out of the tree and attract birds to the tree with a feeder hung in it. The caterpillars were killing my tree!

  4. Jeanette, I read several articles discussing the need to get rid of them because they can overtake your trees and kill them. I have no doubt. The webs were huge!

  5. Those caterpillars are super cool, but really damaging. They really can totally kill a tree within one year! We had to take a whole hedge out because of them!

    I am going to look up that Outdoor looks really interesting.

  6. We just got our book and I am super excited to start the Outdoor Hour Challenge, too. We are going to try to start with the first one for autumn, which is perfect because we start school next week!


Thanks for visiting our blog. Feel free to leave me a comment.