This is the 2nd summer that this small blackish worm is totally eating my beautiful vine. I sprayed it with insecticidal soap last year but it didn’t kill them and they are back again this year. Can you tell me how to get rid of them. My vine is on our fence and is about 40 feet long and until last year was beautiful and very healthy
Thank-you for contacting Toronto Master Gardeners with your question.
It is difficult to identify the pest from the photo you have provided. Many insects look like worms but are actually caterpillars. The Virginia Creeper (Parthenocissus quinquefolia) is a member of the grape family and can experience infestations of a type of caterpillar, the Grapeleaf skeletonizer. Your pest, however, seems to be smaller and more “worm-like”, possibly a cut-worm of some kind. These often attack vegetables by chewing through stems, but they can also attack the leaves on vines such as the Virginia creeper. They usually retreat to the soil or fallen leaves during the day and come out to feed at night, whereas your photo shows the worms feeding during the day.
You can try using an insecticidal soap to kill the worms, but as you noted last year, it is not always effective. Most sources seem to agree that the best way to get rid of any worms/caterpillars is to hand pick them and throw them into a bucket of soapy water. With a large vine, such as yours, this may not, unfortunately, be practical. With some types of worms/caterpillars it is possible to knock them off of the leaves with a strong spray of water.
Here is a general guide to help identify types of leaf-eating pests:
This resource sorts out the various types of larvae:
Here is a link to some information about cut worms: