I have small green worms on my hibiscus plant eating the leaves; what are they and what do I do to get rid of them?
The Gardener’s Answer
Hello, Mary: Without seeing the actual culprit I cannot give you a specific answer, although from what you have described it sounds like it could be the larval stage of a few different insects. There are a few different insects that attack hibiscus but the most common problem associated with hibiscus is the Mallow sawfly (Atomacera decepta). In the larval stage they look like small green caterpillars with black heads. They are not technically a caterpillar so Bt is not effective but hand picking is an organic option for getting rid of these worms. Using a foliar spray such as Sevin is also an option although not organic. It really is best to have the insect identified before using any chemical spray just to make sure you are using a product that will be effective. The sawfly larvae feed on the underside of the foliage, leaving a lacy appearance. For a positive identification you can take a sample to a local garden center with a knowledgeable staff or to your County Cooperative Extension Service. Visit the McCreary County Web site at: //ces.ca.uky.edu/mccreary/
Typically plants are more susceptible to insect and disease problems when they are not growing in optimal conditions. This stresses the plants out and the insects are a secondary problem. Make sure your hibiscus, either tropical or perennial, are growing where they are getting at least six hours of direct sunlight and plenty of moisture.