Biological Control For Spider Mites May Be Most Effective

Q: We have a client with a very large interior-scape. One of the most numerous plants is an Alexander palm. We have been fighting spider mites on these palms for a couple of years. We have tried a large number of products, including insecticidal soap. Unfortunately, we get only temporary relief and within a week or so the spider mites are back with a vengeance. Do you have any control recommendations? (L.P.)

A: You may want to consider utilizing a species of predatory mite to control spider mites. We have had success adopting this approach. There are several different species of mites commercially available that you might want to consider. Most of our successes, however, have occurred when we have utilized Phytoseiulus persimilis. This mite is available from a number of different commercial insectories. For example, you might want to contact Rincon-Vitova Insectories at 800/248-2847. The specific number of mites you’ll need and the requirements for releasing them successfully should be discussed with your supplier.

We have released these mites on Alexander palms during a four-week period to establish the predator. Excellent results were seen within two weeks of the first application. Maintaining the mites so they will continue to control the spider mites will likely require periodic reintroduction of the predator. This should be discussed with your supplier. Keep in mind that the initial expense might be considered high in comparison to what you’ve been doing. However, utilizing predatory mites is not only effective, but will reduce the need for continual use of insecticides and will ultimately result in lower costs.

Jeffrey Tucker is president of Entomology Associates, Houston, Texas.