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It’s that time of year again and the usual suspects are beginning to appear. Last week I went over a pest that we see this time of year that does detrimental damage to pecans. This week I am looking at another one. This very colorful worm (a.k.a. caterpillar) on your azaleas is an Azalea Caterpillar (Datana major). They are very destructive little critters. In large enough numbers, they can defoliate an entire bush. Often, they are not noticed until the damage is already done.

The azalea caterpillar hatches around mid to late-August, earning the name Labor Day worms. The eggs are on the underside of the leaf and packed in as a tight cluster of white eggs numbering 80 to 100. The eggs will hatch, and the young caterpillars will emerge having a yellow body with black stripes and a red head. As they grow, they will molt to a black body with yellow dots, the red head may or may not, turn almost purple. The way to distinguish caterpillars from other insects, like sawflies, is by the three sets of legs near the head. The azalea caterpillar will raise its head and curl its tail when disturbed to form a shape like the letter “C”. There are a few others that do this but not many.

Upon eating their fill of your azalea, they will crawl down the plant and burrow into the soil to pupate. It is here that they will spend the winter. In late spring they will emerge as adult moths and begin the process all over again. Do not worry about handling these caterpillars, they are completely safe. They may, however, regurgitate yellow juice onto your hand.

In a homeowner situation it is best to pick the caterpillars off of the bush and smash them or place them in a bucket of soapy water. You can pick them off by hand if there are just a few or, you can shake the bush to remove them. If the infestation is bad, you may need to go to a product containing B.t. (Bacillus thuringiensis). This is a natural, organic product that will control the young caterpillars. It is marketed under names such as DiPel. Spinosad is another organic approved insecticide that will work on caterpillars and some beetles. There are insecticides that will work such as Acephate (Orthene) or pyrethrin-based insecticides that end in -thrin. These insecticides are much more harmful to the beneficial insects on the bush, so beware of aphid or spider-mite spikes after using an insecticide. This is due to killing all the beneficial insects that are predators of these pests.

Azalea caterpillars will only feed on rhododendron species for the most part. There has been documentation of feeding on blueberries, however. So, if you have other azaleas, rhododendrons, or blueberries be sure to check them all!

If you are having an issue in your home garden or landscape, send your questions to Gene Fox, Consumer Horticulture Agent with the North Carolina Cooperative Extension Service, please email Gene at gene_fox@ncsu.edu or call at (252)946-0111. You can also ask to speak to a Master Gardener! On Mondays and Wednesdays between 10:00 and 12:00, they are on the Greenline to answer all your home horticulture questions. Check out our Facebook page, Beaufort County Master Gardeners, for The Plant of the Week and Food Garden Friday. We are having an Extension Master Gardener Volunteer training starting in September. If you would like to know more about this program, please plan to join us on August 12 from 9:00 – 12:00. Until then, Happy Gardening!