Scale Insects and How to Control Them on Your Houseplants

by | Jan 9, 2018 | 14 comments

In this, the second installation of the insect invasion series, we are going to talk about scale. We talked about aphids in the first installation. The second plant I saw a few weeks ago was located at a library; a large Schefflera arboricola that I noticed right away. The shiny leaves caught my attention from across the room and it compelled me to walk over to inspect it. The extensive problem was more apparent as I walked up to the plant and MY FEET STUCK TO THE CARPETING! The plant was so covered with scale, the carpet was covered with sticky honeydew, which I mentioned in the first installment is insect excretion. YUCK!

Notice the honeydew dripping

Two types of scale

There are two types of scale; hard or armored and soft. The hard scale does not produce honeydew, so we know that the scale on this plant is considered soft scale. The honeydew on this plant is excessive. Scale starts out as crawlers which means just what it says, they crawl around until they find a place to settle down and start eating.

What is the problem?

So the first thing to do when you feel there is a problem with your plant is to find out what the problem is. Is it cultural? Water, light, soil, etc. Or, does it have an insect or mite attacking? After you’ve found the origin of the problem, identify it. The identification of the problem, i.e. insect, is key in figuring out the solution and treatment. If your plant is infested with spider mites, for example, you are not going to use an insecticide, since mites aren’t insects. The chemical wouldn’t work  and spraying your plant willly nilly with whatever chemical you have, is not a good idea. Chemicals should be used sparingly and only after completely reading the label.

These leaflets are completely covered with honeydew (scale excrement)

Can it be saved?

In my opinion, this plant is unable to be saved, in this particular situation. Why?  #1 It’s in a library. #2 No one is paying too close attention to this plant or it would never have gotten this bad. (How could the custodian not feel the stickiness of the floor?!) #3 Because it is a public building, they can’t really spray anything. I’m not sure they would even be able to treat the soil. The really weird thing is the same plant less than 20 feet away, is fine, but probably not for long. Even in your home, deciding whether you want to take action or just dump the plant is a personal decision. Some people do not want to spray anything in their homes, even if organic or considered “safe”.

A clean plant less than 20 feet away from the infested plant.

Move infested plants

One of the first things you should do if you discover you have insects on your plants is to move them away from your other plants. I can show you what happens when you don’t. Even if you do move them, the plants around them may already have bugs, but they may not be apparent yet. Keep a close eye on plants that have been close to infested plants. Below is a type of bird’s nest fern covered in scale.

Scale on a bird’s nest fern, Asplenium

Armored Scale

I had this prayer plant below, tucked in among a group of other plants. Thus the reason I didn’t notice the problem right away. I do know it started on a neoregelia bromeliad as I removed that first when I noticed it had this problem. I wasn’t sure what it was but asked an entomologist friend, and she said it was armored scale. And I should have known it wasn’t soft scale or mealybugs, because there is no honeydew, that sticky residue soft scale, mealybugs, and aphids leave behind after sucking the juice from the plants, otherwise known as excrement.

Armored scale on a prayer plant

Armored scale

Armored scale

I think you can see how I mistakenly thought this was mealybugs. The fuzzy white stuff certainly look like mealybugs. But again, no honeydew should have been my first clue. I have never had this armored scale. And, I also found out it isn’t easy to get rid of. I threw the neoregelia away, it was so bad. I also threw away this prayer plant.

Control

So, how DO you get rid of the scale? Persistence is key. It may take a few treatments of whatever you use.

If you only have a few insects on your plant, using alcohol and a cotton swab and just wiping them off works well. You just have to keep checking the plant to make sure you get the bugs that may hatch from eggs that are hidden. Neem oil is also a good option. I use a product called Bonide Rose Rx in the ready-to-spray form. It is already mixed and ready to spray on the plants. I’ve also just received a sample of Azasol which contains a high percentage of azadirachtin, which is derived from the seeds of the neem tree, so it is stronger than regular neem oil. I will report on its effectiveness later. There are also systemic insecticides that work against these hard-to-control insects. These can be sprayed on the plants, but applying it to the soil and watering it in works better. It moves through the plant, making the entire plant poisonous and when the insects eat the plant, they die. This should be used carefully around children and pets who may also chew on your plants.

Inspect plants often

Remember, if your plant seems to be struggling or looks less than stellar, closely inspect your plant for insects or mites. Always identify the problem before taking any action. When identified, definitely take action, even if that is throwing the plant away, if that is what you choose to do to save your other plants. No judgment here.

Have a great week,

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14 Comments

  1. phyllis

    I’ve had wonderful success just using the old standard of a teaspoon of Dawn dish detergent along with a teaspoon of alcohol mixed with about 3 or 4 cups of water in a spray bottle. I spritz when I water and it usually takes about three applications to get rid of mealy bugs and scale. That poor schefflera. If I could, I would hose the plant down in the shower and then try my soap/alcohol mix on it.

    Reply
    • thehouseplantguru.com

      It is sad, isn’t it? How could they not notice it, especially when they approach it and their feet stick to the carpeting?! We can only do better with our own plants! Have a great day, Phyllis and thanks for the comment.

      Reply
      • Karenina

        Does anyone know if scale could lice in the carpeting or the wooden window frame? I ask because when my 40 yr old sheffelera came down with scale, i moved that plant to my workspace (different building). Then I moved a lemon tree to that window/spot, and then it also came down with scale. Just trying to find out if that’s a possibility as I think towards the fall when I hope to put the lemon tree back there, after treating it all summer w insecticide soap spray and/or neem oil spray. Thanks go any advice!

        Reply
        • Lisa Steinkopf

          Hi Karenina,
          I don’t think it would live in the carpet or on the windowsill, but never say never. I will tell you that lemons or any citrus are known for getting scale. I don’t know if it was already there, but it just seems to always happen. I would just keep an eye on it and keep scraping it off. You can also use a horticultural oil or neem to try to smother them as well. A systemic insecticide in the potting medium would also work, but if you get lemons, I wouldn’t eat them. Hope this helps.
          Lisa

          Reply
  2. Jan Wemple

    thank you for the insight! I didn’t realize armored scale also has white fuzz like mealy. Do the scale emerge from the white fuzz?

    Reply
    • thehouseplantguru.com

      Hi Jan, I think they are under it and it wasn’t really as fuzzy as mealybug. I was just giving it a passing glance and assuming it was mealybug. They are living under the white part, sucking the life from the plant! Rotten bugs!

      Reply
  3. Sally

    I have three plants inside this winter. A Christmas cactus, Aloe plant and Jade plant from friend’s clippings. I have tiny black gnat like bugs flying everywhere in the house. Thinking that they are coming from the new soil that I put in the pots, I have sprayed the plants with several insect sprays for indoor plants but cannot get rid of this speedy critters.
    Any suggestions/

    Reply
    • thehouseplantguru.com

      Hi Sally,
      It sounds like you have fungus gnats. They love moist potting medium and live in the top 1″ of it. You need to let your plants dry out more before watering them. Remove the top 1-1 1/2 inches of medium and replace with new. If it is a mix you bought at the store, I would mix in some vermiculite and perlite to make it more porous so it will drain better. This should help. Good luck! Let me know how it goes.

      Reply
  4. Mrs Monique Brien

    Hi there. I have a citrus tree inside (which will be moved outside this week). I have treated it for scale honey dew but there is some on the carpet. Does anyone know how I can get it off?

    Reply
    • Lisa Steinkopf

      I think I would use a carpet cleaner or a spray spot carpet cleaner. I’ve not had it on my carpet, but I know it is sticky. Lisa

      Reply
  5. Lindall Burton

    I had a plant and the water tray would overflow and run over in the carpet. I would see white specks in the overflow pan of water but wasn’t for sure if it was an insect. I started feeling sensation on my ankles and legs of something jumping on me while sitting in this room so I sprayed bleach water and threw out the plant and the infestation moved to the next room and now throughout my home. I have tried pesticides Foggers but it didn’t work. I looked up plant lice, Psyllids and Aphids which I am assuming maybe my issue because I not have bite marks just annoying feeling of something jumping on me when I walk or sit in my home. Do you have advice what I can use to get rid of these little bugs I can’t see but feel. I appreciate your help.

    Reply
    • Lisa Steinkopf

      Hi Lindall,
      I have never heard of anything like that. Are you sure it isn’t fleas or something else? I would capture some if you can and take them to your local extension agent, local garden center, or ask on a Facebook insect identification group. I’m sorry I am not more help. Let me know if you find out anything.
      Lisa

      Reply
  6. Wendy Murray

    We are removing some plants that have scale. I need to know how to clean the rugs near the plants, walls and other areas.

    Reply
    • Lisa Steinkopf

      Hi Wendy,
      I would just wipe them down to get the sticky stuff off. I would use a mild soap, but don’t want to suggest anything specific because I don’t know what you are washing. I would use whatever soap that is appropriate for what you are cleaning. I don’t think any insecticide or anything like that is needed. Lisa

      Reply

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