Houseplant Pests: Scale

Scale insects are arguably the hardest to detect. They come in many colors and shapes, but all 8,000 species have one thing in common: their waxy coating that resembles the scales of a lizard or dragon. This dome-shaped/shell-shaped coating protects the insect as it feeds on the plant's saps, eventually depleting it of life. 

The main reason these pests are so hard to recognize is because of their lack of movement. Adult scale bugs quite literally never move. In fact, they don't even have legs. 😬 How do they get on your plant then, you ask? Some species start off as "crawlers" the size of a pinhead. They crawl until they find a good spot to latch onto. Once they've settled in, they lose their legs and spend the rest of their gluttonous life eating. Other species are simply carried by the wind, hoping they find a good plant to leech off of.

Pretty gross, huh? Get this - scale's needle-like mouthparts are six to eight times larger than the actual bug itself and their excrement can cause mold to form on your plant... they can't get much worse.

If you want to see what scale insects look like IRL, click here.

Treatment

Since these guys can be really tough to spot, chances are, you'll notice your plant's health declining before you actually see the scales. Look out for premature leaf drop and discoloration. If you're lucky, they'll make their presence known early by latching onto the top of a leaf. Otherwise, you'll probably catch them hanging out on the stems and the undersides of your plant:

  1. Quarantine the plant. As mentioned earlier, scales can spread to other plants pretty quickly, even if they look legless. Isolate your plant in another room to keep the rest of your collection safe.
  2. Pick the bugs off. You can use your fingernail to scrape them off quite easily, but we get that that's gross. In our experience, the easiest way to remove them is to dip a Q tip in rubbing alcohol. You can also use mild dish soap diluted with water. Using the Q tip, pick the insects off one by one.
  3. Spray the plant down. Using a mixture of rubbing alcohol and water (1:3 ratio), spray the leaves and stems of the plant. This is strong enough to kill anything you missed, but safe to use on your plant. Make sure to target the underside of the leaves and stem crevices. Avoid direct light when doing this.
  4. Monitor daily. Inspect your plant frequently for any signs of survivors. It may take a couple of treatments before they're gone for good, but with vigilance, they will be defeated. 💪

After you've gotten rid of them for good, give your plant some extra TLC. It's likely stressed from having a bunch of tiny vampires attached to it. Keep it in its preferred light and water it as usual. If it's been 6 weeks since it was last repotted, give it some plant food. It can use a nutrient boost. 

Prevention

Obviously, no one wants to deal with scale insects again after experiencing their first outbreak. Here's what you can do to prevent them from coming back:

  1. Inspect every plant. Anytime you get a new plant, it's wise to give it a thorough inspection and even a spray down in the sink, just in case. Most shops and nurseries are vigilant about pest control, but it's nature and it happens. Look out for yourself and your plants!
  2. Clean your leaves. This is important for many reasons, but a plant with dusty leaves struggles to photosynthesize properly, making it a weak and easy target for predators. We like to mix apple cider vinegar and water (1:2) in a bowl and use a reusable cloth to gently remove unwanted buildup. 
  3. Use pesticides. Neem oil is a naturally occuring pesticide that you can safely spray your plants with to prevent pest outbreaks. It also has anti-bacterial and anti-fungal properties.
On the bright side, once you get a hold of the problem, it's actually quite easy to manage. If you're ever uncertain if you have a pest problem on your hands, you can always text our SMS Plant Doctor Hotline at (646) 430-8699.