Question
Hi Will,

Some of my houseplants are covered with fine webbing that suggest spider mites. Can you please offer a safe, effective treatment for spider mites?

Thanks,
Sue


Answer
Hi Sue,

Spider mites are very tiny and they look like dust particles to the naked eye, often hiding on the undersides of leaves. By the time they start making webs, they are already well established and difficult to eradicate.

Plain soap and water, insecticidal soap, and Hot Pepper Wax can all be used safely to treat spider mites. The key with all of these products is to get 100% coverage of all leaf and stem surfaces - top and bottom. If you miss a few of the mites, which is easy to do because they are small enough to reside between spray droplets, then they will start to reproduce and you will have another infestation again in a few weeks.

Try to spray in a location where you can thoroughly drench all leaf surfaces without worrying about all the run-off. Run your fingers along leaf and stem surfaces to help get complete surface coverage (use rubber or latex gloves to avoid skin irritation. It is also advisable to re-spray again about 5 days later to get any mites that you may have missed the first time.

The best mite prevention is vigilance. Any mite-prone plants, such as palms, should be checked every week for early signs of mites - look for "dust" particles on the undersides of leaves. Treat the mites at the very first sighting. They are much easier to eliminate in the early stages.

Spider mites often are introduced on newly acquired plants or by plants that have been outside. You may want to spray such plants before you bring them inside. Spider mites also prey on plants that are under stress. Thus, it is important to keep your plants healthy by providing good light and proper water.

Spider mites can reproduce in the 54 to 110 degree range, with the optimum range of 85 to 90 degrees. In unfavorable conditions (cooler temps, shorter day length, reduced plant vigor) they go into diapause when they hibernate (don抰 feed or lay eggs). Pesticides are ineffective during diapause because the mites are not feeding. When favorable conditions return, the mite population can explode and give the appearance of coming out of nowhere. Nitrogen fertilizers encourage tender new growth, which is very attractive to mites.  Mites suck the chloroplasts out of green cells. Mites use webs to travel from one feeding spot to another.

Now you know everything there is to know about these critters! Please let me know if any of this is unclear or if you have any additional questions. If you would like to e-mail me some photos, I may be able to provide some additional insights.

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Regards,
Will Creed, Interior Landscaper
Horticultural Help, NYC

You can E-mail me directly at: [email protected]