August turns up all kinds of pests and disease in the garden. You may be noticing large webs across the terminal branches of your trees now, similar to stretched pantyhose. Look closely and you will see small caterpillars inside, each marked with parallel rows of black spots on the back. The fall webworm (Hyphantria cunea) is very noticeable now but at this stage, the caterpillars stay in the web and feed inside on the leaves. The web is unsightly but their feeding will not kill the tree. However, this would be a good time to cut the branches and bag the webs, caterpillars and all. Close up the bags tightly and dispose of in the trash. Later, after the last molt, they leave the web and crawl all over the tree. Then they spin cocoons, pupate, and emerge as white moths. If you are not able to bag the web don’t despair, there are many natural enemies of the fall webworm. Another tactic is to spray the first generation in the spring with horticultural oil, Bt (Bacillus thuringiensis), or insecticidal soap before they create the web. Don’t try to burn them out though, it is too dangerous to the tree. For more information on plant pests and diseases, check out the Plant Pests and Diseases tab on pegplant.com.
Subscribe to Pegplant’s Post, a free monthly newsletter about gardening in the Washington DC metro area. Each issue lists at least 50 local gardening events, recently published gardening books, tips, advice and articles about gardening in this area, and a giveaway. Just enter your e-mail in the subscribe box above.
Peggy’s lectures and workshops
Saturday, June 15, 10:30 am to noon, Workshop on 13 culinary herbs, Richard Byrd Library, 7250 Commerce Street, Springfield, VA. Free
Follow me on TwitterMy Tweets
follow me on Instagram