Pest of the Month: Fall Webworms

August 29, 2018

Pest of the Month: Fall Webworms

Pests can be a huge, damaging or aesthetic issue for the trees in your backyard. To ensure that you are informed about the dangers that could be lurking around your landscaping greenery, we are going to be tackling a common pest every month.

This month we are going to be talking about Fall Webworms. While these are mostly harmful to how your trees look, many homeowners want to make sure they don’t have them on their property at all.

We are going to cover what this pest is, what they look like, the damage they cause, and how you can control them yourself/with the help of a professional. Let’s get started!

What are Fall Webworms?

Fall Webworms (Hyphantria/Cunea/Andrew C/ Rentschler Forest Fairfield OH/Wikipedia Commons

These pests are a moth in the family Erebidae, and are known mostly for their larval stage, which creates the gauzy, webbed nests on tree limbs of hardwoods in the late summer/early fall.

For the most part, these are an aesthetic pest that won’t cause damage to your healthy trees. They are very well known to arboriculturists and tree service businesses as they are commonly requested to be removed.

One generation is born per year, and is seen mostly in the northern parts of the United States. The adult moths lay hundreds of eggs on the underside of leaves, and the larvae stage is what you see creating the huge webs on your trees in the fall.

The adult webworm is a large white and fluffy moth, with wings that expand to about 30mm.

The Damage Fall Webworms Cause

By Andrews C via Wikipedia Commons

Like we said before, your healthy trees are not going to be damaged or killed by this pest. However, they are extremely unsightly during this time of the year. The larvae create enormous, white, fluffy webs over the leaves and branches of your trees, which tends to look unpleasant.

However, if you do decide to let them stay, this pest actually feeds over 40 species of birds, so you would be doing the local wildlife a favor by letting them reside in your trees.

One of the best parts of your landscaping is getting to enjoy the natural beauty of the plants and arrangements. If you do decide to remove these pests for aesthetic reasons, know that many other people do the exact same thing every year.

How Do I Treat Fall Webworms?

So how do you treat these pests?

If you decide that you want to rid your trees of the webworms, there are a few different methods you can try out.

One option you have is to use dormant oil. This is an oil that you spray over your plants and trees when they are dormant, usually in late winter or early spring. It works by either suffocating the pests by covering up their breathing tubes, or by directly penetrating their outside cuticle and destroying their internal cells.

This is a great method because it works on most pests and their eggs, and it is something they aren’t going to build up a resistance to. However it is important to note that if you spray your trees with this after they begin budding for the year, you may kill and/or blacken some of the new growth. This is why it is only recommended for dormant times of the year.

You can purchase this product online or at any local garden supply store for a fair price.

There are also some insecticides that will work well on controlling fall webworms as well, although these are more toxic than using dormant oil. Sevin, Malathion, and Orthene are all options that work well for this species of pest. However, keep in mind that Malathion does leave a residue on the leaves of the tree.

Lastly, you are able to burn them out as well. This is definitely an intense and dramatic method of removal, but it certainly works well. This is not recommended by too many people, and it may be more prudent to consider the first two methods we discussed.

Some people will use a propane torch attached to a long pole to burn out the webs, and simply seek them out by eye. We don’t really recommend this method, as it really isn’t the safest way to go about removing a pest. If you are going to do this, make sure to follow standard safety procedures and be as careful as possible.

If you are unsure of the best steps to take to remove fall webworms from your landscaping, contact Arborist Now or tree experts in your local area for advice! We hope you found our guide informative, and that your trees stay healthy and webworm free this fall!