Hello Tamara,

Do you have any images of the worms? This will help our expert when suggesting a solution.

Tamara:

I cannot ID the pest with out a good picture. I am doing some guessing so I will need some help from you. You stated there was webbing. Are the caterpillars on this webbing? I am sure the caterpillars are small, but a picture may be helpful. Using Raid would ‘NOT’ be a good idea as that pesticide is for different insects. 

Do you know what kind of tree this is? How long has this pest problem been going on?

Thanks for any additional information you can share.

Rich

Tamara:
This is a good picture of the insect, thanks.

You have tent caterpillars. Do you know the name of the tree you have here as it might make a difference in the management/treatment of the pest.

I have copied some links that may be of help to you. It’s about the pest not the plant it eats.

Alder (Alnus)-Western tent caterpillar | Pacific Northwest Pest Management Handbooks (pnwhandbooks.org)

Management-biological control

See: Biological Control of Nursery Pests

Tent caterpillars have many natural enemies. Some birds eat caterpillars, and small mammals consume the pupae. The larvae of a tachinid fly parasitizes the caterpillars.

Management- cultural control

Overwintering egg masses can be removed and destroyed when practical.

Management-chemical control

Dormant-season spray oil spray

Apply with enough water to cover the entire tree thoroughly. Apply in delayed-dormant period to destroy overwintering egg masses.

Let me know if you have additional questions.

Rich

Tamara:

This is not a Douglas Fir.

I am guessing a non-native ornamental fir. The treatments listed in my earlier note should still apply.

Rich

Most welcome, let me know how it goes.

Rich