Spider mites are among the world’s most common and destructive house plant pests.
These herbivorous insects are just about 0.9-1.25 mm long. To the naked eye, they’re but small, mobile dots. These dots can be red, white, tan or black. Quite easy to overlook and underestimate.
Spider mites are capable of causing extensive damage. That too, in a very short span. They feed on the leaves’ cell material. The results—the leaves develop unsightly light colored spots, turn bronze or yellow, and finally, drop off.
In the absence of prompt, proper treatment, the infected plants have little chance of survival.
How to Identify Spider Mites?
Spider mites are resistant to common pesticides. That’s why it’s essential to verify you have a spider mites infestation before even thinking of corrective measures.
Insecticides such as pyrethroids and carbaryl kill minute pirate bugs, thrips and other predatory insects that feed on spider mites. So, if you don’t have a spider mites issue, applying a pesticide can actually create one.
The easiest, surest way of verifying whether your indoor plants have spider mites is using a 10X hand lens. Shake the leaves while holding a white paper sheet underneath. The mites are quick, so you’ll need to be quick with your observation.
Spider mites have oval shaped bodies, with 8 legs and 2 eyespots on their heads. Look on the leaves’ undersides. That’s where these mites build their colonies. A single colony can house hundreds of mites.
The presence of dense webs around the fruit, twigs and leaves indicates a severe infestation. Keep in mind, not all webs are made by spider mites. Your friendly neighborhood garden spiders build them too. Only, the spiders typically use theirs to catch bad guys such as spider mites.
So, how do you differentiate a spider’s web from the spider mites’?
Look at the web’s shape and location. Spiders usually build webs at a plant’s top area and between branches. These are typically layered and don’t engulf the plant’s foliage.
Spider mites, on the other hand, build webs that enclose the foliage, stems and branches. Their webs are fine and sticky. In most cases, you’d be able to spot tiny spider mites on the webs.
Which House Plants Are Most Affected by Spider Mites?
Spider mites aren’t too picky about the types of indoor plants they feed on. The best indoor plants, including ornamental flowering and foliage plants, shrubs and small fruit can all fall victim.
The mites do prefer warm, dusty conditions. They reproduce during the hot weather and their numbers can swell heavily during the months of June-September.
Plants facing water stress are particularly susceptible to spider mites infestations. So, unless you’re growing the best plants for home that can withstand droughts, irrigate regularly.
How Do House Plants Get Spider Mites?
There are multiple ways how your indoor plants can get spider mites. Here are the most common ones:
Bringing in a new plant that has spider mites on it.
Using non-sterile potting soil for repotting indoor plants.
Placing the house plants outside during the warmer months.
Spider mites can be transferred indoors when you bring in flowers or fruits from your garden.
In addition, they can come indoors via the screens of open windows or doors, even on your clothes and shoes.
How to Control Spider Mites on House Plants?
Once you’re certain you have a spider mites problem, don’t lose any time. While spider mites can be fatal to your plants, spider mite control doesn't require calling in an interior plant service. Here are some of the best and easiest ways to get rid of spider mites:
Isolate Affected Plants
If spider mites are limited to just one or few of your indoor plants, it’s best to isolate them. Move them to a closed room or garage where they can get the required sunlight and temperature conditions while being treated.
Wash Them Off
Spider mites relish dusty conditions. Spraying infected plants with a hose can wash off the dust and the mites. Use a sink or shower area to wash down your plants. Make sure the water pressure is just strong enough to remove the mites without harming the plant.
Target the leaves’ undersides when spraying. You can repeat this every day until the mites are all gone. In addition, dust the interiors regularly to prevent dust buildup.
Apply Plant Based Oils
Plant based oils such as neem oil, cottonseed oil and canola oil are potent natural pesticides. Commercially available plant extracts (Acaricides) that contain garlic, mint oil, clove oil and other naturally derived oils are also highly effective. These are safe for pets, humans and beneficial insects, but work like a charm against spider mites.
For application, mix the plant based oil with water and spray it onto your plants. Make sure to cover the entirety of the plants, particularly the undersides of the leaves. You can alternately use a piece of microfiber cloth for the task. Dip it in the oil-water mix and gently rub it onto the surface of your plants.
Use a clean, dry cloth to wipe away any excess oil-water mix. Repeat after a week.
Use Insecticidal Soaps
Insecticidal soaps are a stronger treatment than neem oil. These can kill spider mites on contact. If you feel washing and applying neem oil isn’t doing the trick, thoroughly apply an insecticidal soap all over the affected plants.
Do not use plant based oils or insecticidal soaps on indoor plants that are water-stressed.
The impact of direct sunlight on plants covered with insecticides can severely burn the plants. So, only use the insecticidal soap during evenings or remove the plants from the sun when applying.
Not all insecticidal oils and soaps are safe for every indoor plant. Read the label carefully before use. When in doubt, try out the oil or soap on a section of the foliage and observe its effects. If the foliage seems to have been burnt or damaged, discontinue using the product.
Managing spider mites isn’t difficult. Just follow these tips, wear protective gloves when handling insecticides and keep at it until the spider mites are all gone for good.