Spider mites are annoying, tiny houseplant pests that pop up out of seemingly nowhere. This post will cover how to identify these irritating arachnids and what we can do about them when we find them!
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What are spider mites and what do they look like?
Spider mites are nearly invisible plant pests because they are incredibly small (only .4 mm or .02 in), which makes them capable of accumulating in large numbers virtually unnoticed. To the naked eye, they appear as specks of dust on the tops or undersides of leaves.
Spider mites thrive in colonies (check out the photo below of one massive colony). As a type of arachnid, they are not a true insect. This is important to note because some insecticidal controls may not be effective for spider mites.
The most common houseplant variety of spider mite is red (like you see below), but there are over a thousand species of varying colors (green, yellow, tan, brown, and black).
Spider mites are able to reproduce very rapidly, creating large infestations in short amounts of time.
Look at this terrifying, but amazing photo of a spider mite colony below!
Signs your plant may have spider mites
Here are some signs and symptoms that can help you to determine whether your plant is suffering from spider mites:
- yellow or brown spotting or stippling on leaves caused by the mites sucking sap from the leaves
- webbing between leaves/branches or on the underside of leaves (this webbing is where spider mites earned their name)
- dust-like accumulation on the tops or bottoms of leaves; if you hold a white piece of paper below the suspected leaf and tap it or shake it, you may see specks fall onto the piece of paper. Those are likely to be spider mites
- yellowing, dying leaves without a logical alternate cause (like aging growth or overwatering)
Photo below of webbing between leaves and branches from spider mites
Spotting on a leaf caused by spider mites
Magnified look at spider mites gathered on the underside of a leaf
Leaf damage and red dust accumulation from spider mites
Highly-infested plant with webbing
How to control spider mites
1. Wash away the mites
Spraying off your plants when you water them can be surprising effectively at removing a lot of spider mites. It is important, if using this method, to wash both the tops and bottoms of leaves since spider mites often dwell on the undersides.
Washing your plants is also a great idea to remove dust build up on the leaves, to wash away other potential pests, and to help keep your plant looking healthy and beautiful.
2. Spray with pesticidal sprays (home and store-bought options)
Neem Oil and Soap Spray
Mix 17 ounces water, .5 tsp neem oil, and .75 tsp mild dish soap in a spray bottle.
It’s best to test the spray on a portion of the plant to make sure it will tolerate the spray well. I am not the best at testing the sprays before applying myself, but I have heard that some plants can be sensitive to neem.
I use Plantonix brand of neem oil: Here is a link to Amazon, where I purchased mine.
I have been currently using Dr. Bronner’s Peppermint Pure-Castille Soap which is known for being gentle on plants and the peppermint oil also helps to repel pests. Link to Amazon for Dr. Bronner’s.
I also use Dawn Ultra Gentle Dishwashing Liquid and have had success with it; it’s just a lot more expensive. Link to Amazon for Seventh Generation Dish Liquid Soap, Free & Clear
If you are interested in the glass spray bottles I use, here is a link to Amazon for those as well.
Rubbing Alcohol and Soap Spray
To make this one, mix 4 ounces rubbing alcohol, 1.5 tsp mild dish soap, and 16 ounces water in a spray bottle.
This spray can use the same mild dish soap as the neem oil spray, but replaces neem with rubbing alcohol. It might be an easier solution to create because many people have rubbing alcohol already on hand and is pretty effective at pest control.
I find this particular spray most effective when I coat the leaves and wipe them off with a gentle cloth. The neem oil spray I do not wipe off the leaves, I just spray the plant thoroughly.
Store-bought spray solution
If you prefer a ready-made solution, one great option is Garden Safe Houseplant Insect control spray. It has been effective at pest control without damaging my plant as long as I don’t allow it to pool on the leaves of the plant.
I would not personally use this on my outdoor plants because I worry about harming beneficial insects, but I would have no problem using it indoors!
3. Introduce beneficial insects or predators
Beneficial insects and predators are a great way to control pests because they do the work without you needing to do anything besides introduce them!
This option may not be super appealing to someone who hates bugs, but as long as you are okay with a few extra bugs (besides the pests you already have), I highly recommend it!
Both green lacewings and ladybugs eat all of the most common houseplant pests (spider mites, aphids, mealybugs, scale, thrips, and whiteflies) besides fungus gnats.
If you want something that will be highly interested in spider mites (instead of a broad spectrum option), there are several varieties of predatory mites that you can introduce which are extremely effective at controlling spider mite populations.
You can order beneficial bugs online from many vendors for overnight shipping to your home!
4. Increase the humidity near your plants
Spider mites thrive in dry conditions, which makes the dry winter season a perfect breeding ground for them. They do not like humidity and moisture, so one way to combat them (and make your plants happy at the same time) is to up your humidity.
I bought a LeVoit Humidifer recently for in the room where the majority of my plants live. The great thing about this humidifier is that you can set the humidity level you want the room to be at. I am currently keeping the room around 50%, which doesn’t sound all that high when you read about what some people try to maintain for their plants.
However, 50% is 10 to 20 percent higher than my home would naturally be at this time of year and not high enough to promote mold growth or condensation on the windows of the room.
This humidifier is a bit of an investment, but its totally worth it because of the large tank and all of the settings and options. Here’s a link to the product on Amazon, if you are interested: LeVoit Humidier on Amazon
I like being able to track the humidity and temperature in this room, so I use my little ThermoPro to do that. Check out the lowest humidity! 30%! Yikes.
Here’s the Amazon link for the ThermoPro, in case you are interested in using one of these as well: ThermoPro Digital Hygrometer & Indoor Thermometer
Will spider mites spread to nearby plants?
Yep!! Unfortunately, spider mites are one of the most efficient houseplant pests at spreading from plant to plant. They can utilize webbing to travel to a new plant, simply crawling (if plants are touching), or even a small breeze. I remember reading somewhere that spider mites can blow in through an open window even.
A lot of people find spider mites to be one of the absolute worst houseplant pests. What do you think is the worst houseplant pest to deal with? Share it in the comments below!
Note: The Amazon links in this post are affiliate links, which means that if you purchase using this link I might get a small percentage of the purchase. It is no additional cost to you to do this. I only link to products that I use and love.
Resources used for the post:
Click to read last week’s article: Digging into the Weedy, Wonderful World of Oxalis, or False Shamrock Plants