The mere mention of spider mites can cast a chill into a plant lover’s heart. These tiny, voracious critters are by far the most common pest affecting Calatheas. Even if you’ve never run into this problem, you should know how to spot the signs and combat an infestation; the quicker you take action, the better odds of survival your plant will have. This article will explain how to recognize and destroy spider mites on your Calathea.
Spider mite damage causes your Calathea’s foliage to wilt and curl, and the scarring from their bites appears as a dusting of pale dots across the leaf surface. The mites themselves are so tiny that they’re hard to see, but you can often spot their eggs or the wispy webbing they spin on the leaves. Treat the plant with dilute solutions of soap, rubbing alcohol, or neem oil; for best results, rotate between these treatments every few days.
Quarantine an infested Calathea far from any other houseplants while you’re treating it; otherwise, the spider mites may spread throughout your collection. Be prepared to battle the bugs for a few weeks at least, repeating the treatment every 3-5 days. If you find that your topical treatments are ineffective, try upping the dosage or applying a soil drench of neem oil. We’ll talk more about those options below.
What’s Eating My Calathea Leaves?
The first step in treating your Calathea is correctly identifying the problem. So let’s talk about what spider mites are and how to tell if they’re attacking your plant.
Though you’ll sometimes hear people refer to spider mites as insects, they’re actually a type of arachnid, more closely related to ticks and spiders than to other garden pests like aphids and thrips. They like to live on the underside of plant leaves, where they feed by puncturing the host’s cells with their mouthparts and drinking the sugary juices inside.
Their name comes from the sticky webs they create to shield themselves and their eggs from predators. Spider mites also use this webbing to drift on the breeze like hang gliders, meaning that they can occasionally invade your home through an open window or settle onto plants you keep on the balcony. As if that wasn’t bad enough, they reproduce at a breakneck pace – less than a week after a mite hatches, it will begin laying new eggs of its own.
Does My Calathea Have Spider Mites?
Spotting the signs of a spider mite infestation early is often vital to keeping your Calathea alive. We’ll go over the typical symptoms, beginning with the earliest ones and moving on to the signs of a severe outbreak.
In general, the first indication of a mite problem is drooping, shriveled foliage. The thin leaves of Calatheas are quite vulnerable to dehydration, and spider mites can drain them quickly. They tend to develop brown spots and curl inward at the edges, rolling up like scrolls.
You might also notice that your Calathea no longer tilts its leaves up at night. This daily routine, known as nyctinasty, is the signature behavior of plants in the Marantaceae family. It relies on moisture in the joints below the plant’s leaves, so the predation of mites often shuts it down.
You’ll have to do a bit of investigation to tell whether these early signs result from mites or some other problem such as underwatering. Check the surface of the wilting leaves for the distinctive pattern of damage that spider mites leave behind: a random stippling of tiny, pale dots that give the leaf a dusty or faded appearance.
Take a look at the bottom of the leaves, too. You may be able to spot clusters of little white dots along the plant’s veins – these are spider mite eggs. The lower surface might also feel sticky due to the webs the mites are building up. By the time the webbing is easily visible to the naked eye, you have a serious mite problem on your hands.
In the advanced stages of a spider mite attack, a Calathea begins to look like a hollowed-out shell of its former self. Its leaves are limp and shriveled, their formerly vivid patterns reduced to faded echoes by scarring from bites. At this point, your Calthea likely can’t be salvaged.
How to Get Rid of Spider Mites on Your Calathea
Spider mites are tenacious little creeps, and some houseplant owners give up in despair after repeated treatments fail to eliminate the pests. To save your Calathea, you’ll need to mentally prepare for what could be a long fight. But with patience, persistence, and thoroughness, you should be able to rid your plant mites.
We’ll walk you through the process one step at a time.
Step 1: Quarantine Your Calathea
If spider mites are colonizing one of your plants, it’s only a matter of time before they spread to others nearby. Move the infested plant well away from the rest of your collection. If you can shut it away behind closed doors, that’s even better. Social distancing isn’t enough here – spider mites call for a full-on lockdown.
After you’ve moved your Patient Zero, check its neighbors thoroughly for mites (wash your hands first to avoid letting any pests hitch a ride with you). They’re often hard to see in the early stages of an infestation. One helpful trick is to hold a piece of blank white paper underneath the leaves and then tap or shake the stems. If the paper is suddenly covered with tons of tiny dots like fine grains of pepper, you’re probably dealing with mites.
Step 2: Clear the Deadweight
By the time you diagnose a spider mite infestation in your Calathea, some of its leaves may already be so chewed up and shriveled that there’s no saving them. At this point, all they’re doing is providing a home for mites, so get rid of them.
Find yourself a good set of pruning shears and wipe the blades down with a disinfectant solution like rubbing alcohol or a 10% dilution of household bleach. Then snip the dead or dying leaves off. There’s no need to cut all the way down to the base; sometimes, new leaves will emerge partway up a trimmed stem. Keep disinfecting your blades between snips.
Step 3: Choose Your Weapons
You’ll need to use some sort of chemical treatment to kill the spider mites before they kill your Calathea. The common choices include:
- Isopropyl alcohol, also known as rubbing alcohol. Dilute it to a 1:4 ratio with distilled water.
- Dish soap. Use something without harsh chemical additives like degreasers. This one is a popular pick because it includes peppermint oil, which has some natural pesticidal properties. Mix roughly one teaspoon of soap into a liter of warm water.
- Hydrogen peroxide. The 3% concentration sold at your local drugstore should be safe for your Calathea and deadly for mites.
- Neem oil. This is a natural pesticide that disrupts the life cycle of spider mites, slowing their reproduction as well as killing them. Shake up ⅓ teaspoon of soap in a liter of water to help the oil emulsify, then add 1 teaspoon of neem.
Mix up your chosen solution thoroughly. It’s probably a good idea to make a big batch because you’re going to need at least a few applications to rid your plant of mites. Use distilled or filtered water whenever possible – Calatheas are sensitive to the chemicals often found in tap water.
Step 4: Spray Down Your Calathea
Shake up your mite-killing mixture and use it to fill up a spray bottle. Then spritz your plant down from bottom to top.
Be as thorough as you can. Spray the stems, the undersides, and the tops of the leaves. Get into every nook and cranny you can reach, including the rolled-up tubes of newly emerging leaves. Spider mites can hide in the tiniest of crevices, and these chemicals will only kill the mites that are actually hit by the spray.
Step 5: Wipe Down the Leaves and Stems
You can use a microfiber cloth or a cotton pad for this step, but you may get better results with something slightly more abrasive, such as a paper towel or an old, scratchy makeup brush.
Dip your wipe or brush in the same solution that you used to spray down the plant. Then clean the foliage, starting at the base of each leaf and moving from the central vein out to the edges. Support the leaves with your hand to keep them from tearing. This step won’t just kill the mites – it also removes the protective webbing that shields them from liquid pesticides.
Get the front and back of each leaf, then wipe down the stems from top to bottom. As in Step 4, thoroughness is critical here. The more mites you kill with this first pass, the fewer will remain to repopulate the plant after this mini-apocalypse.
Periodically reapply your mite-killer solution to your brush or cloth as you wipe down the plant. To be extra thorough, you might want to give your Calathea one more head-to-toe spray after you’ve cleaned the protective webs off the plant. If you used a mix containing soap, rinse the foliage off after letting it sit for 10 minutes or so.
After using neem oil, keep your Calathea out of any direct sunlight for at least a few days. Neem is a powerful pesticide, but it increases the likelihood of sunburn, and Calatheas are already vulnerable to scorching. If you usually put your plant in a spot that gets a couple of hours of direct sun, move it someplace that only receives reflected or filtered light.
Step 6: Repeat and Rotate
Don’t expect a single cleaning of your Calathea to completely eliminate spider mites. A single treatment almost never gets the pests at every stage of their life cycle. There will likely be new hatchlings within a few days.
That means you need to come back and kill the next generation, and probably the next several generations after that. Treat your plant every 3-5 days until you’re confident you’ve completely wiped out the infestation.
You should also change up which chemical agent you use – never hit the mites with the same treatment twice in a row. Because they breed so quickly, spider mite colonies can rapidly develop resistance to pesticides. Changing up your treatment greatly reduces the chance that they’ll build up a population-wide immunity.
Alternative Methods
Sometimes you’ll run into an especially resilient spider mite colony. If these pests just won’t go away despite weeks of regular spritzing and wiping, you may need to try other strategies.
One option is to increase the concentration of the chemicals you’re using – for example, stepping up the dilution of rubbing alcohol from 1:4 to 1:3 or 1:2. Be careful, though – Calatheas have sensitive foliage. When you’re considering applying a harsher dose, try spraying it on a single leaf first, waiting a week or so to see whether it becomes discolored or shriveled.
Another option is to drench the soil with a neem oil solution. The plant’s roots will take up the chemicals as they drink, infusing it through all of its tissues. This means that the spider mites can’t survive by hiding in some inaccessible corner – they’ll ingest the pesticide every time they take a bite of your Calathea.
Use 1-2 tablespoons of neem oil per gallon of water. Once per month, use this mix when watering your Calathea, and keep this up until you stop seeing spider mites. Make sure you choose a cold-pressed oil; more intense processing strips away the ingredient that kills mites.
It’s probably a good idea to continue occasionally spraying your Calathea with alcohol, dish soap, or hydrogen peroxide during this period. And once again, be extra careful about sunburn.
One final trick: find something that eats the things eating your plant. Spider mites have a number of natural predators, and if you don’t mind adding a few more bugs to your home, you can order them from garden supply companies.
Ladybugs are a popular and reliable choice – they’ll chow down on spider mites by the truckload. For something a little more inconspicuous, try predatory mites from the genus Phytoseiulus – they look like bigger, redder versions of spider mites, but instead of plants, they eat other bugs.
Preventing Spider Mites on Calatheas
A rigorous treatment regimen may cure a Calathea, but the best option is to prevent your plant from being infested in the first place. There are a few strategies that will reduce the odds of your Calathea falling prey to spider mites.
First of all, keep the plant’s environment humid. It’s no accident that spider mites tend to crop up in the fall and winter – they hate moisture and thrive in dry conditions. Setting your Calathea on a pebble tray or near a humidifier will help discourage mites.
It’s also helpful to take a few minutes each day to mist your Calathea and gently wipe down its leaves (both the tops and the undersides) with a soft cloth. This will add a bit of moisture and help clear off wandering mites before they can settle in and start raising families. It’s also a good opportunity to inspect the foliage for early signs of pest damage.
If you see any large red mites that are visible to the naked eye, try to avoid disturbing them. These are the predatory mites we mentioned above – they help to keep your plant clear of spider mites and other harmful bugs, so let them go about their business!
Finally, don’t keep your plants too close together. Many indoor gardeners cluster tropical plants like Calatheas near one another to increase local humidity. This is a good idea, but you should still allow for a bit of space between plants. If their leaves are touching, a spider mite infestation on one plant will spread like wildfire to all the others.
Other Calathea Pests
Although spider mites are the bugs you’re most likely to battle as a Calathea owner, there are a few others that you might encounter, such as:
- Aphids. These sap-sucking insects are much larger than mites, appearing as clusters of small teardrop shapes on the stems of a plant. They produce a sticky substance called honeydew that may incubate mold.
- Scale. Tough, armored pests that find a juicy spot and clamp down, becoming extremely hard to dislodge. They look like odd lumps or nodules on the surface of the plant.
- Mealybugs. These are related to scale, but instead of hard shells, they’re covered with a fuzzy-looking white secretion. They like to hide in out-of-the-way crevices on your Calathea.
The same treatment plan recommended for spider mites should also get rid of these less common pests. Always treat scale insects should with rubbing alcohol, and you’ll probably need to scrape them off with a Q-tip doused in the stuff – simply wiping the plant down may not be enough to clear them away.
Final Thoughts
Spider mites are scary, but they don’t have to be a death sentence for your Calathea. If you follow the steps we’ve outlined above, and you’re diligent about sticking with your treatment, you’ve got a good shot at saving your plant. Remember to keep your Calathea’s environment humid in the future – that will make it an unattractive target for these insidious pests.