Spider Mites and How To Control Them on Your Houseplants

by | Feb 19, 2018 | 2 comments

Spider mites on houseplants. They suck!

As you know, if you live in the Midwest, the heaters are on full blast and have been since last fall. Our skin is dry, our hair is crazy because of static electricity, and we are drinking more water. If you think you feel dry, imagine how your plants are feeling.

When the air gets dry, I swear a dinner bell we can’t hear rings, and the spider mites flock to the table. The leaves of your houseplants are the piece de resistance on the menu. Then, out of the blue, you start noticing the leaves of your plants getting splotchy. They may also have a silvery sheen to them. Yikes.

The spider mites are feeding on the juices of your plants. Most likely you will not see the mites unless you get your magnifying glass out and really look. They usually are hiding on the back of the leaves, but if present in large numbers, they may be on the front, too.

spider mites on houseplants
Webbing on a leaf, created by two spotted spider mites

Two-spotted spider mites on houseplants

The most common mite indoors is the two-spotted spider mite, Tetranychus urticae. Let’s talk a little more about these little “buggers”. If you look at the bottom of this picture below, you can see the two spots on the body of the mite. These spots are the accumulation of body waste showing through their transparent bodies. Yuck!

Spider mites and webbing
When this close, you can see the two spots on the spider mite

Spider mite anatomy

They are in the same class, Arachnida, as spiders. They look like insects, you say. Yes, they do, but the difference is that they have 8 legs, among other differences. The front four legs point forward and the four legs in the back face backward.

Baby mites

And the weird thing, the baby mites have 6 legs like insects, but on their last molt, they come out with 8. Their cone-shaped heads called gnathostome, are between their two front legs. They have no antennae and no abdominal segments like insects.

How spider mites on houseplants damage them

They also have no jaws but have things called stylets that come out of the mouth, called the stylophore. These stylets aren’t hollow tubes as insects have, but are like solid rods.

Scale, mealybugs, and aphids use the tubes to probe deep into the phloem of the plant and suck up the juices. It’s like drinking through a straw.

Mites stab into the leaf surface, and as the liquid leaks out of the cells, they suck up those droplets.

Where the fluids drain out of the cells, the cells die. We see the mottled or spotty appearance of the dead cells on the leaf surface. Mites kill cells, but insects do not. The next three pictures show the damage mites have done to a leaf.

Spider mites damage on houseplants
The back of the leaf showing the damage done by the spider mites
Spider mites on houseplants
The damage from these sucking insects is extensive on this leaf
spider mite webbing
The webbing with the spider mites obviously in sight


Webbing indicates spider mites on houseplants

You may not notice the problem until the webbing the mites make is visible. This webbing protects the mites and also acts as the roads they use to get around your plant.

Once you see webbing, the problem is quite advanced. If you use a Swiffer or dust cloth of some sort to dust your plants, they can hitch a ride from one plant to the next.

They may also attach to your clothes or the fur of a pet walking by and brushing against the plant. Even the small breeze we create as we walk by could help them move to the next plant. Sneaky little buggers!

If you suspect a problem and think it may be mites, tap your plant over a white piece of paper. They will fall onto the paper and move. Hopefully, you catch them early before they become a huge problem.

Control of spider mites on houseplants

So how do you prevent or control the mites if you have them. First of all, mites love hot dry air and reproduce faster in warmer temps. Keep your heat a bit lower, but most importantly, wash your plant often and keep the humidity elevated.

I like to use pebble trays under plants that are especially susceptible to mites, such as palms. Another thing I like to tell people about is heat deflectors for heat vents. I have them on most of my heat vents so that the drying air isn’t blowing right up onto my plants.

It is important not to have air blasting directly on your plants. If the mites get out of hand, they can completely defoliate your plant. I have seen this happen.

If you find that you have them, I would still take my plant to the shower or sink and give it a good spray down. Then I would use a horticultural oil or insecticidal soap (works on mites, too) or a miticide on the plant.

Remember, insecticides do not work on mites as they are not insects. ALWAYS read the label to make sure you are using the correct product for the problem you are dealing with.

spider mites on housepants
The damage done on this leaf as well as the webbing is obvious to the naked eye


Cyclamen mites

You may also encounter cyclamen mites, Steneotarsonemus pallidus in your home. These are most often found on cyclamen and African violets. The middle of your violets will be fuzzier and the centers tightly packed together. Distorted or smaller than normal leaves are also indicators.

These mites, unlike spider mites, like higher humidity. They are living where the new foliage originates, where the young supple leaves are. You would need a large magnifying glass or microscope to see these mites. Most likely you won’t see them with the naked eye.

If you suspect your plants have these, it is better to get rid of them. I know African violet growers who have thrown away their plants because of cyclamen mites. There are chemicals that will kill them and that decision is up to you.

I hope this post helps you identify and deal with spider mites. They aren’t easy to get rid of, so the prevention is best. But if you do find some, deal with them swiftly so they don’t get out of hand.

Happy growing! If you have any questions, please leave it in the comments below and I will answer it to the best of my ability.

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2 Comments

  1. Elise

    This is very helpful! At what point would you say that it’s not worth trying to get rid of the spider mites on a plant? I have a dieffenbachia that was neglected in a corner and got a pretty bad case, and I’m worried that they will spread to my other plants. I’m planning on showering it off if I can, but I’m still trying to decide if the fight is worth it or if I should sacrifice the plant for the sake of my others. Thank you!

    Reply
    • Lisa Steinkopf

      Hi Elise,
      I’m glad it was helpful! I would try washing it off, and maybe spraying with Mite-X or Neem oil, following the directions given, of course. If you make sure it doesn’t dry out and keep an eye on it, it should be fine. Lisa

      Reply

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