Spider Mites on Orchids

(Question)

Last week I discovered that one of my orchids had a pretty severe infestation of spider mites. I’ve had the plant since February. It came up pretty suddenly and the infestation was such that I had to , sadly, get rid of the plant. Heartbreaking. That orchid was situated next to two other orchids I have. A second one is now showing signs of spider mites: white webby clumps under the leaves, little “spots” on the flower petals, stickiness on the leaves. I immediately moved it away from the other orchid – hopefully it’s not to late. Please tell me what to do to get rid of these horrible creatures. My orchids are otherwise very healthy – they have been blooming blossoms of six and 10 on a shoot. They are like family to me. Desperate to stop the invasion.

(Answer)

Yikes, that’s not good!  It does sound like mites!!

Mites thrive when it’s warm and dry, but when it’s humid and wet the mite activity slows down and can be controlled.  I would suggest, for overall plant well being, that you either mist your plant regularly or place the plant pot on top of some pebbles in a tray with water in it – make sure your plant is not sitting in the water.  Both of these will raise the humidity around your plant and should begin to slow down the mites’ life cycle.  Many enthusiasts give their orchids a short tepid/warm shower once a month in order to simulate the type of growing conditions that orchids experience in their native habitat in more tropical climates.

A gentle spray of water can be used to dislodge mites from the orchid leaves.  You can also use water and a soft sponge to gently wash each leaf, especially the leaf undersides as this is where mites like to hide.  Make sure you wipe each leaf to get the mites, their tiny webs and as many eggs as possible off the plant.  Continue these treatments a couple of times each week for at least 5 – 6 weeks.

If this approach is not helping then spraying with an insecticidal soap should do the trick – again making sure to completely spray over both sides of the leaves and following the product label instructions carefully.

As mites can live in the soil, another suggestion would be to take your orchid out of the infested soil it is presently in, completely flush the root system with distilled water and to repot it in fresh uncontaminated orchid soil.

One orchid expert recommends putting the affected plants outside once the weather is warm enough – the mites’ natural enemies plus the more challenging environment will often get rid of the problem.

If these strategies do not work, you may have to use a miticide.  In that case, consult your local nursery as to which ones can be used on orchids.

Keep the plants isolated from one another (and other plants) until you are sure the infestation is over.

And just in case it’s not spider mites, here’s an overview of the types of insects and mites that can affect orchids, and how to recognize and to control them:  Canadian Orchid Congress’ “Do you have bugs? Don’t panic”.