The Life Cycle of a Fall Webworm Moth

Hi everyone! I couldn't help but notice this white moth on a leaf but I couldn't get very close to it. Thankfully I have a zoom lens.

OMG! It is a Fall Webworm Moth and she laid her eggs on the leaf! This was a first for me so I was very excited. I documented the life cycle and I am happy to share this with you.

In the north, fall webworm moths are usually pure white but in the south, they have black spots. The one that I am showing you is the northern fall webworm moth, (Hyphantria cunea). In late spring, females lay their light green, round eggs in a single layer on the leaf of the host plant. The eggs are covered with white scales from her abdomen. Their preferred host trees are Hickory, Elm, Alder, Willow, Birch, Mulberry, Oak, Pecan, Walnut, Sweetgum and Poplar.

Here you can see how hairy her head is.

In one to two weeks the eggs hatch. From the time I saw the moth and eggs, ten days had passed when I first saw the Fall Webworm Moth caterpillars. They look like little worms.

The web spinning caterpillars immediately begin building their sticky silk tent over leaves at the end of a branch that may extend to other branches. The tent is tough and not easy for predators to break into, which allows the caterpillars to eat and grow safely. They eat the leaves, leaving the larger veins and midrib behind. The caterpillars never leave the tent until they are mature.

The caterpillars are inside these leaf rolls and will eat their way out.

Five days later, the tent had expanded to two branches and the caterpillars have grown. When they have eaten all of the leaves on one branch, they have to go to the next closest branch for new leaves.

The caterpillars make a mess of these ornamental trees but that is as far as the damage goes.

Four more days had passed and the tent now covers five branches.

I saw the tent shaking on this day. If the tent is disturbed, the caterpillars will make jerking movements, all at the same time. I believe this is done to scare away potential predators.

Three more days have passed and the leaves on this branch are completely gone and in the caterpillars tummies.

Three more days have passed and the tents are empty. You can see the holes.

From the time the eggs hatched, the caterpillars were in their tents for three weeks. I don't know if they left on their own accord or if birds got to them. According to perdue.edu, the caterpillars feed on the leaves in their tent for six weeks. This tent was in my neighbor's yard so I had no way to see what happened to them.

To my surprise, I found a full grown caterpillar three weeks later on my trash can. Was this a lone survivor?

Yay! I captured its face.

Mature caterpillars are 1-1.5 inches long and as you can see, they have a black head and are covered with tufts of long hairs.

Their bodies have a pair of black spots on each segment.

When fall webworm caterpillars leave the tent, they go in leaf litter or bark crevices to pupate.

Fall webworm moths are nocturnal and are attracted to light. I had the back porch light on and that is why this one came to my door. I took photos to show you what the abdomen looks like.

The silk web that fall webworm caterpillars make is called a 'tent'. Do not get that confused with the Tent Worm Moth and their caterpillars.

Thanks for stopping by!

All photos are my own.

Information Source: perdue.edu, tamu.edu, ufl.edu, thoughtco.com