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Question 2

The leaves of my crape myrtles are covered with yellowish-green insects. Many leaves have developed yellow spots and there is black, sticky substance on the leaves.What should I do?

It sounds like you have an infestation of a sucking insect, probably the crape myrtle aphid. Aphids feed on plant juices and excrete a sticky substance known as honeydew. The honeydew falls on the leaves below them and frequently a black mildew, called sooty mold, grows on the honeydew.

The larvae of a lady beetle (the larger insect) will feed on large quantities of crape myrtle aphids (the smaller insect) and provide natural control when aphid numbers are low. Photo Credits: Theresa Friday, Santa Rosa County Extension

Typically, if the crape myrtle is large and healthy, treatment may not be necessary. However, if you are seeing significant damage, you may need to control the aphids. In north Florida, crape myrtle aphid populations generally peak between late June and early August. Therefore, control measures should begin by the first week of July.

The least toxic chemical controls include insecticidal soap or horticultural oil. Be sure to follow the label directions. Because aphids reproduce so quickly, repeated applications may be necessary. For other options, refer to the UF/IFAS publication, Insect Management on Landscape Plants, at http://edis.ifas.ufl.edu/IG013.

One thing to consider is that aphids are food for many of our area's beneficial insects. Read more about this amazing interaction at http://edis.ifas.ufl.edu/IN663, a UF/IFAS publication on the Crapemyrtle Aphid.