Gardening Help FAQs

Here are answers to some of the most common questions we receive about garden plants. You will find concise information on general gardening techniques as well as plant selection and care. For detailed information on specific plant pests and problems refer to our Common Garden Pests and Problems page.

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Horticulture Questions and Answers

What insects are common on honeylocust trees?

The honeylocust has become a popular tree among homeowners because of its fast growth and availability. Its open growth casts only a light shade and allows most lawn grasses to grow beneath the trees. As the honeylocust has become more popular, the insects that attack it have increased. The mimosa webworm, a relatively new insect pest in Missouri, is one of the most damaging insects. There are two generations of the pest in this area. However, these generations overlap to the extent that some larvae are usually present on infested trees from June until September. The larvae of the second generation are often so numerous during late summer that they skeletonize all the leaves on the host trees and leave webbing over most of the limbs.

If feasible, webworms can be controlled by pruning out the webs when the insects are inside, for example, on cool days or at night. Control is also gained by destroying the webs and knocking the worms onto the ground. They can be chemically controlled by spraying in early June and early August with any of the following: Orthene and Sevin. The web must be penetrated with the spray for good control. Be careful when applying chemicals and follow all label directions. If the problem is allowed to continue, the trees will lose vigor and become stressed allowing secondary pests to attack. Older trees, whose vigor is reduced, should be pruned quite severely once every 2 to 4 years to maintain vigor. The cultivar 'Moraine' is reported to be more tolerant to the worms than 'Skyline', 'Shademaster', 'Imperial' or 'Sunburst'.