Scale on houseplants is a large category of pests encompassing 8,000 known insect species of insects in the suborder Sternorrhyncha. This suborder is identified by the rearward position of its mouth relative to its head. A few of these species—aphids, white flies, and mealybugs—are so common and distinct that they are known as their own type of houseplant pest. Nevertheless, that leaves countless species of bugs that are collectively known as scale.
How to Identify Scale on Houseplants
There are two general types of scale:
- Hard Scale: This bug will create an armored shell, or hard covering. The scale itself lives under this protective shell, which prevents it from moving once created.
- Soft Scale: This type of scale creates a waxy film as a protective covering. They can move around the plant if forced but do not like to do so. These bugs can vary in shape, but they almost all produce honeydew.
These bugs are known for looking like simple spots of discoloration, but you may also catch them during a more active phase depending on the species. Scale will find a good place to latch on to the houseplant and begin to steal nutrients from the leaves or stem of the plant. They have a typical life cycle of about two months. They lay eggs which quickly turn into crawlers which will spread out in search of a good place to mature into an adult. Once they reach maturity, they will never move again, but when in their crawler phase, they can infest nearby houseplants. They tend to appear in clusters more so than other houseplant pests.
Plant damage starts with yellowing leaves, then leaves that drop prematurely, and whole branches may begin to die back. Be sure to isolate houseplants with scale to make sure the infestation does not become a more widespread problem.
Scale Pest Control and Treatment
Mild infestations can be treated by promptly removing the bugs from the plant and applying a timely insecticide. You can remove the bugs by rubbing, picking, or squeezing. A cotton swab soaked in alcohol can make this process a lot easier. Insecticidal soaps and oils can be used to treat hard to reach scale, but do not persist long enough to kill the eggs/larval form of the bug. Even after removing a mild scale infestation, you should isolate the houseplant from other plants and inspect it for signs of new scale.
Neem oil is a good option for protecting most houseplants from infestations. Another strategy for scale and houseplant pest control is to fight bugs with bugs. Ladybugs eat scale and other types of houseplant pests. You can buy these ladybugs online, have them delivered, and then introduce them to your houseplants. This is also a good time to evaluate how you’re caring for the houseplant. Weakened plants from overwatering or underwatering, too much or too light exposure, or pot-bound plants are all more likely to suffer from scale.
Cost-Benefit Analysis of Treating Houseplants for Scale
Scale is a stubborn houseplant pest, especially when not caught in the earliest stages. If you see only a few isolated spots of scale, it’s probably worth trying to remove the bugs and apply preventative treatment. For larger houseplants, an infestation may be too advanced to remove the bugs, but still localized to one branch or area of the pot. You may be able to cut out the scale infestation, while saving and nurturing rest of the plant back to full health.
If you have an extensive or persistent scale problem, the best solution is probably to discard the entire plant and give the pot a deep cleaning before trying a new plant. There is no shame in losing a plant. Some plants fall victim to scale and other pests even with perfect houseplant care. At this point, you just want to make sure the problem isn’t widespread throughout the home. If you are deeply attached to the houseplant in question, we recommend finding the healthiest remaining growth and see if you can repot and regrow the plant.
Not sure what you’re seeing on your plants is scale—or maybe a special kind of scale? Check our complete guide on houseplant pest control.