Mark Your Calendar: the 70th Annual Oregon Orchid Show & Sale is April 22-23, 2017 in Portland, OR

Spider Mites


Spider mites are very small and because of this they can be difficult to identify. Oftentimes, one can only see them with a magnifying glass until the problem is severe. The symptoms of spider mite infestation can be seen with the naked eye and you should keep watch for them. The primary symptom is light stippling on the leaves and sometimes the buds of the flowers. You may also see fine webbing but only when the infestation has become quite severe. Spider mites naturally inhabit the undersides of leaves and the lower, older leaves. They don’t travel quickly and a mite may spend its entire life on one leaf of a plant. Their life cycle is one-two weeks (faster in warmer temperatures). Repeated treatments are needed to insure that all generations of the pest are killed.

The key to killing spider mites is first recongnizing that you have an infestation and then repeated treatments. Because spider mites are so small, they can go a long time without notice. This is exacerbated by the fact that they don’t travel much, so there can be an acute problem in one part of your growing space that won’t be noticed until it gets out of hand.

Treatment Details Indoor?
Insecticidal Soap Use a soap that indicates that it kills spider mites and can be used on orchids. If it doesn’t mention orchids but is safe for African violets (or “ornamentals”)it will probably be ok. Be sure to treat all angles of the plants as the mites usually live on the undersides of leaves or at the base of the plant. Repeated treatment is key because the soap will not kill the eggs. Depending on the temperature, spider mites regenerate every 7-14 days, so a regiment of spraying every couple of days for that length is the minimum treatment. Safe indoors.
Predators Since you already have mites living in your growing space, why not get some more! Only, this time you should buy some predator mites to eat the bad ones. While these can be expensive but might be worth the cost – especially if you don’t have time to commit to repeated treatments. They tend to be a more thorough solution than spraying (because you can always miss spots and allow further generations of spider mites to live) and they do the work for you. That said, if you are dealing with other pest issues and treating them with chemicals you will also be killing your expensive predator mites. Safe indoors, but may not be easy to keep confined.