5 Common Dieffenbachia Pests: How to Identify, Prevent, and Treat Them
Dieffenbachia makes a stunning houseplant with its showy tropical foliage. Unfortunately, there are some common pests that love them as much as we do! Gardening expert Melissa Strauss discusses the potential threats to your dumbcanes and what to do about them.
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Dieffenbachia, which goes by the common name “dumbcane,” is a gorgeous, tropical perennial. Its large, showy foliage adds drama and vacation vibes to your houseplant collection. It’s an excellent air purifier, and in Feng Shui, they are thought to bring prosperity, positive energy, and good fortune.
This is a terrific choice for those lower-light areas of the home. They prefer their exposure to be indirect and moderate. Too much light will stress this plant, and can scorch the soft leaves. Well-draining soil and consistent moisture are the ideal conditions, so ensure your container has good drainage.
Overall, dieffenbachia is not especially difficult, but I find it particularly susceptible to nuisance insects. It’s important to stay on top of this one to prevent unwanted infestation. Of course, the best prevention is to examine any new plants you bring home for pest damage.
Let’s talk about some of the common pests that could be a problem for your dieffenbachia. Then, we can figure out how to get rid of them and how to prevent them from returning.
Fungus Gnats
Fungus gnats can be so annoying and unsightly. These little bugs find mold and fungus irresistible, so it’s a telltale sign of overwatering when they show up. If you notice mold growing on top of your soil, fungus gnats will likely be close behind.
Though the adults won’t do much to harm your plant, they aren’t fun to have around. The real problem is their larvae. These little guys can tear up the root system of your dieffenbachia, feeding on the root hairs and even tunneling through the roots.
While it’s rare for there to be an infestation terrible enough to kill a plant indoors, you’ll probably want to get rid of these pests anyway. They can get pretty annoying and spread to other plants. Several generations can be present simultaneously, and females can lay a ton of eggs.
How to Identify
Most species of fungus gnats are tiny, only about 1/8 of an inch long, though some are larger. Up close, they might remind you of a tiny mosquito. They are delicate, with fine antennae and small wings. They are not strong fliers, so you’ll see them dancing around the soil irregularly.
How to Prevent
Keep fungus gnats at bay by maintaining good watering hygiene. Don’t overdo it, and make sure you use well-draining soil and a container with drainage. Re-potting regularly will cut down on decaying matter in the soil.
How to Remove
Nematodes like to eat fungus gnats, but introducing them at home may not be your thing. Yellow sticky traps are good for catching these and all types of flies. You can trap them with a bowl of apple cider vinegar, dish soap, and sugar placed nearby. Rinsing the soil with hydrogen peroxide will kill the larvae, but make sure to flush it out. Don’t leave it for very long.
Scales
Scales are tiny armored insects that suck the sweet sap out of your plants. An infestation can cause wilted leaves, stunted growth, and an overall lack of vigor.
For a healthy dieffenbachia, catching these pests early on will ensure no lasting damage. Just be sure to keep a close eye on it afterward. They will weaken it and leave it more vulnerable to other pests and diseases. An infestation of an already weakened plant can result in death.
How to Identify
You’re unlikely to see scales moving around. In fact, they typically look like small bumps just growing on the stems and leaves. There are hard and soft scales, and the hard ones are more difficult to eradicate. They are often dome-shaped but can also be flat.
Another issue caused by scale insects is mold. They leave behind a sticky, sugary excrement called honeydew. Black sooty mold can grow in this mess and interfere with photosynthesis.
How to Prevent
To protect and prevent scales and their damage, it’s important to keep your dieffenbachia healthy. Fertilize regularly, and make sure that it is getting the right amount of light and water. A healthy plant stands up better to insect damage.
You can spray your plants with horticultural oil or neem oil as a preventative, but make sure that you use non-toxic products in the home. Spraying your plants outdoors and bringing them in afterward is best.
How to Remove
Spraying the leaves with insecticidal soap or horticultural oil will help eradicate soft scales. Armored scales have a waxy coating that protects them from most of these products. A cotton swab soaked in alcohol is their worst enemy. The alcohol breaks down the coating, and you can just wipe the scales away. Use 70% or less concentrations of alcohol.
Spider Mites
If you’ve ever been up against an infestation of spider mites, you know they can be a real hassle. These incredibly small arachnids suck the juice out of your plant’s leaves, and the result is sickly, yellowing and pale foliage. Initially, the damage looks like small dots all over a leaf. If you can catch them at this stage, you will save a lot of headache for the plant.
How to Identify
Spider mites are incredibly tiny and almost impossible to detect on their own. However, they spin super fine webs beneath leaves. These webs are a telltale sign of an infestation. As the infestation advances, you’ll notice the foliage issues I mentioned above.
How to Prevent
Spider mites don’t like humidity, but dieffenbachia does. Maintain a humidity level above 50%, and make sure to water your plant as needed. A drought-stressed plant will be more susceptible to damage. Dust your leaves regularly as well. Wiping them down with neem oil is a good preventative measure.
How to Remove
At the first sign of these pests, isolate the plant to avoid their spread. Once they move in, they are difficult to get rid of. Try wiping down the leaves with a solution of castile soap and water. Make sure it’s heavily diluted.
Mites breathe through their exoskeleton, so horticultural oils effectively treat them. It will suffocate them. Mites have a number of natural predators, so you may want to set your dieffenbachia outdoors for a few days and allow nature to do its job.
Aphids
Aphids are probably public enemy number one in the garden. They can make it inside and get to your houseplants as well. These sap sucking pests drain your dieffenbachia of valuable nutrients and leave behind a sticky, honeydew mess.
Aphids reproduce quickly and can take down a plant in no time. It’s important to identify and treat them right away. Fortunately, they are easy to see and have a distinctive appearance.
How to Identify
These insects are soft-bodied and small with tubelike bodies. They can be black, green, brown, yellow, or red, though I find the red ones are more pink. You’ll find them clustered in groups on stems and under leaves. They occasionally have wings, but most do not.
How to Prevent
Outdoors, you can prevent these by not over-fertilizing and keeping weeds and debris cleared away in the garden. Certain plants are far more attractive to them than others.
They typically come into the house on another plant, so be sure to inspect new plants for these pests. Because they are easy to see, they tend to be less of an issue indoors.
How to Remove
Neem oil and insecticidal soaps are effective in eradicating aphids. A solution of castile soap and water will work as well. These also have many natural predators, so if all else fails, set your plant outside for a few days. Ladybugs and lacewings like to feed on them.
Mealybugs
Mealybugs are a pest that I have personally dealt with on my dieffenbachia. Though they can do a significant amount of damage if left to their own devices, they aren’t that difficult to get rid of. Their damage is similar to scales and aphids in that they drain the plant of nutrients and leave behind a mess of honeydew and black sooty mold.
How to Identify
Mealybugs are small, but of these pests, they are certainly not the smallest. You can see them clearly without magnification. They have a white or pale pink waxy coating that makes them appear fuzzy. You’ll often find them clustered up on stems and in crevices where they can hide.
How to Prevent
Keep your plants healthy to prevent major damage. Inspect any new plants you bring into the house, and don’t overwater or over-fertilize.
How to Remove
You can break down their waxy coating with soapy water or insecticidal soaps. Neem oil is effective in disrupting their reproductive cycle. As with armored scales, an alcohol-soaked cotton swab is great for dissolving that waxy coating and wiping them away.
They can be hard to eradicate in one treatment physically, as they tend to lay eggs in crevices that are difficult to get to. Mealybugs also have a lot of natural predators, so leaving them outdoors is usually effective. Ladybugs, lacewings, and spiders like to eat these pests.
