Common Houseplant Pests

My Garden Life
August 6, 2018
Table of Contents

Your pampered indoor plants present a tasty smorgasbord for houseplant pests. The healthier your plants are the more enticing they will be. It’s possible for a plant to coexist with a few bugs but the problem comes when one or two insects multiply into a full-blown infestation. Too many insects feeding on a plant can cause significant damage. There is also the risk of pests spreading from one plant to other nearby plants. Help keep your houseplants safe by learning to identify common indoor insect pests and how to control them.

The Most Common Houseplant Pests

Mealy bug

White cottony masses found along the stems and underneath the leaves are actually soft-bodied insects. Mealy bugs use their sharp mouth parts to pierce plant tissue and feed on sap.

mealy bugs on houseplant

Mealy bugs on your houseplant – what to do

You may have heard the saying ‘prevention is always better than cure’. Preventing mealy bugs from infesting your house plants can be done by checking plants before bringing them in.

Symptoms of a full-blown attack are a white fuzzy mass on leaves and stems. Mealy bugs also secrete honeydew which can create an environment for fungus to grow. The key is not letting their numbers get too high so you’re able to minimize any damage caused.

Regularly inspecting your houseplants for pests will ensure that a major infestation of mealy bugs doesn’t happen. Controlling mealy bugs is much easier if you can catch it in the early stages and at that point you may be able to wash the bugs off the plant. Don’t wait for an infestation to build up and become unmanageable.

Spider mites

Spider mites feed and lay eggs on the undersides of leaves. They’re quite tiny; a magnifier is helpful for identifying them. Plant symptoms include webbed areas along the stems, yellowing foliage, and tiny eggs and debris on the leaf undersides.

Houseplant Pests - spider mites on houseplant

Spider mites on your houseplant – what to do

So if you want to keep spider mites off your precious houseplants, make sure they have moist conditions by using humidifiers for the room or periodically spraying them with water mist. You can also try adding peat moss into their potting mix.

Scale

Smooth, rounded bumps along stems and on leaves are the protective shells of the scale insect. Scale use their needle-like mouth parts to feed on plant sap, so they can remain in one location for a long time.

Houseplant Pests - scale insects on houseplant

Scale bugs on your houseplants – what to do

In order to rid your houseplants of scale insects, start by removing any that you can find with a fingernail or soft toothbrush. Be warned: adults may be more resilient and require a bit of force before they come off the plant. Rinsing plants with water is good for getting bugs out from between leaves. You may have to tackle this several times to fix your scale bug problems.

The next step is to follow this with an insecticide that can kill any of the larvae. Even if you’ve removed every bug by hand, the larvae are so small and hard to see without a magnifier, meaning they may still be present on your plant. Treat with neem oil or insecticidal soap depending on how bad the infestation is.

Fungus gnat

Tiny flies that are attracted to moist soil where they lay their eggs. The larvae, once they emerge, feed on decomposing organic matter in the soil and plant roots.

Houseplant Pests - fungus gnats on houseplant

Fungus gnats on your houseplants – what to do

If you find fungus gnats, allow the soil to dry to a depth of one to two inches between waterings. This not only kills larvae and inhibits the development of eggs, but will also make the soil less attractive to egg-laying females.

Fruit Flies

It’s also important to know the difference between fungus gnats and fruit flies to be sure you’re correctly identifying your houseplant pests. Fruit flies are tiny flies that are attracted to ripening fruits and vegetables – not to your houseplants – but they’re often confused with fungus gnats. The easiest way to tell them apart are the fruit fly’s distinctive red eyes.

Fruit fly sitting on a piece of celery.

Aphids

Soft bodied insects that suck plant juices through the leaves and stems. They’re often found feeding on the soft tissue found at a plant’s growing tips, tender new leaves, and undersides of leaves. Plant symptoms include curled, distorted new growth and a sticky residue on the foliage.

Houseplant Pests - aphids on houseplant

Aphids on your houseplants – what to do

Fight off pesky insects with a mix of dish soap and water. Aphids are one type of insect that can be kept at bay by spraying or wiping the plant’s leaves with a mild soapy solution. Spray leaves, reapply every two to three days for up to two weeks.

Thrips

These tiny winged insects can be difficult to see without a magnifier. They may be easier to identify by the damage they cause. Thrips puncture plant tissue by tearing it away with their strong mouth parts and they suck the plant juices from the wound. Areas where they’ve scraped away plant tissue are thinned and often appear as brown or silvery blotches.

Houseplant Pests - thrips on houseplant

Thrips on your houseplants – what to do

You can get rid of these houseplant pests with just one easy trick: shake the branches, catch them on a cloth under it, then throw out everything on the cloth in order to kill all those pesky bugs.

Whiteflies

Whiteflies can be found on the undersides of leaves or flying near a plant. They pierce plant tissue and suck out the juices. Plant damage can include yellow, mottled foliage and leaf drop.

Houseplant Pests - whiteflies on houseplant

Whiteflies on your houseplants – what to do

When you observe whiteflies on your plants, it’s important to take swift action. The first step is blasting them off with water or spraying insecticidal soap and following up two to three times as needed.

Roaches

Roaches are common indoor pests whether or not you have houseplants. Normally they aren’t a problem, but houseplants do provide moisture and shelter that a roach could find appealing. Don’t entice roaches by putting un-composted food scraps or beverages into your houseplants.

Houseplant Pests - roach on houseplant

Roaches on your houseplants – what to do

Allowing your potted plants to dry completely between waterings can help reduce roaches on your houseplants. Excess moisture in the plants or standing water around the bottom tray is attractive to thirsty roaches.

Where do houseplant pests come from?

It’s surprising how many ways insects can find their way to houseplants. Here are a few of the most common ways houseplant pests can eventually end up on your plants:

  • Fresh produce from the garden or the grocery store
  • Cut flower bouquets
  • Potted gift plants
  • Newly purchased plants
  • Plants kept outdoors for the summer
  • Potting soil
  • Carried in on clothing
  • Open windows – tiny insects can even get through window screens

Managing bug infestations on indoor plants

Rules for managing almost any houseplant pest:

  • At the first sign of a bug problem, move the infected plant away from other plants.
  • If possible rinse the plant with water in a sink, tub or outdoors to try to physically remove as many pests as possible from the foliage.
  • Rubbing alcohol in a spray bottle or cotton swabs dipped in rubbing alcohol can be applied directly on the insects. The alcohol evaporates quickly, killing the pest without harming the plant.
  • Pests can’t survive dish soap. A mix of 1/2 teaspoon dish soap mixed in a quart of water in a hand-sprayer can be sprayed directly on pests.
  • Insecticidal soap is a commercially available product for spraying indoor or outdoor plant pests. Use according to package directions.
  • If the outbreak is small, and you’re not bug-squeamish, insects can be manually removed with tweezers or paper towel.
  • Chemical insecticides for houseplants are available. Check the product label to make sure the insect you are trying to control is listed, that the product can be used on your specific plant, and that the product is safe for indoor use.

Controlling Houseplant Pests

Tips for preventing pest infestations on your houseplants

The best way to prevent insects from taking over your plants is by catching them before they get a chance to “make themselves at home”. Here are some tips for keeping pests from bugging your houseplants:

  • Inspect plants thoroughly at time of purchase. Avoid any plant with obvious pests, including insects flying around the plants.
  • To avoid infecting existing houseplants be sure to isolate a new houseplant for about a month. Keep a close eye on it until you’ve established that the new plant is pest free.
  • Keep plants clean. Remove dead foliage and wash the plant leaves periodically with water.
  • Use a magnifying glass to occasionally inspect plants for pests.
  • If plant has had a serious infestation, replace the soil with fresh potting mix after treatment.
  • Make sure plant gets the recommended amount of light, water and fertilizer (check plant label) to keep it in optimum health.
  • Keep away from cold or hot drafts found near windows, doors, or air ducts that could stress and weaken a plant.
  • Always use sterilized potting mix when repotting plants.

Sometimes, despite your best efforts, it can be hard to get houseplant pests under control. If the population has managed to grow quite large, the plant can become disfigured, defoliated, and unattractive. The best control method, in a case like this, may be to simply discard the infested plant and replace it with a new, healthier plant. Trying to salvage one infested plant can put all of your plants at risk.

Sickly, defoliating potted miniature rose on an office desk.

The insects common to houseplants are highly adaptable and very skilled at hiding within a plant to protect themselves. They can be a little tricky to control, but certainly not impossible, especially if you catch them early. Knowing what to look for and being able to correctly identify houseplant pests can make all the difference in keeping your plants healthy and insect-free.

Fluoride damage in plants

Sometimes fluoride damage in a plant is confused with insect activity. Many sources of public water contain fluoride and while fluoride is good for people’s teeth, it’s not so good for some plants. Watering houseplants with fluoridated water can result in a toxic accumulation of the mineral in the plant’s tissue. The resulting brown leaf tips and edges should not be confused with insect damage. Watering with distilled, rain, or filtered water will prevent your plants from developing this condition.

To learn more about the role minerals can play in a plant’s health see our article, 5 Common Nutrient Deficiencies in Plants.

Leaves of a chlorphytum plant showing damage from fluoride in the water.

12 Comments

  1. Carolyn Holman

    This was great and very helpful
    I had scale along time ago had no idea what it was .I crushed it and spray ed it I was lucky.

    Reply
    • My Garden Life

      Hi Carolyn,
      Good job! Scale are particularly difficult to control because of their protective outer covering. Crushing their “armor” is a good way to expose the soft body underneath and eliminate the insect.

      Reply
  2. Di

    my madagascar has a great big hole in the trunk

    Reply
    • My Garden Life

      Hello Di,
      Is your plant otherwise looking healthy? It’s not uncommon for Pachypodium plants (Madagascar Palm) to suffer areas of rot and leave a hole such as you describe. Often by the time rot is discovered it is too late to do anything about it. The wound will either heal on its own (although the scarring is likely to remain) or succumb to rot if the conditions that led to the rot continue.

      Prevention is the best way to keep your plant from developing rot. Make sure your plant is in a pot with good drainage so water doesn’t accumulate, be sure it’s getting sufficient light such as near a west or south-facing window, reduce watering to once a month during winter, and allow the top inch of soil to dry in between watering. Simply feeling the soil with your finger is a good way to judge whether your plant needs water. If the top inch of soil is damp, delay watering until it is more dry. Please see our article on Common Madagascar Palm Problems for more tips.

      Reply
  3. Freddy

    Some of my Impatiens plants have begun to show tiny clear blobs growing out of their stems. I don’t see any moving insects. The only reference I can find online is to “grape pearls” or “sap balls” that appear on grape vines and are benign. Why would I have them on an Impatiens plant? The leaves on one of the affected plants have some brown areas, but otherwise all seem healthy. I did start a new bag of potting soil–could that be the source of whatever condition this is?

    Reply
    • My Garden Life

      Hi Freddy,
      You might be observing something known as “guttation”. Guttation is the means by which a plant regulates its internal water pressure. Guttation is not uncommon with impatiens, and it can appear along the stem as well at the leaf edges. If there is sugar or minerals within the moisture released that could add some firmness to the droplets.

      Guttation is of no harm to the plant, but it may be more common if the plant is receiving excess water. Not something you can control if Mother Nature is doing the watering, but do make sure you’re not contributing to overwatering. You mention that you used a new potting mix. Potting mixes vary in their composition so if this one is high in moisture-retaining peat or vermiculite, or if the soil is enhanced with water-retaining hydrogel beads or crystals, you may want to keep a closer eye on watering frequency for a couple of weeks. Simply sticking your finger in the soil is the simplest way to check soil moisture. When the top 1-2” of soil is dry to the touch, it’s time to water.

      We did find one image of an impatiens displaying guttation, use the link here for comparison to your plant.

      Reply
      • Freddy

        Yes, that is definitely what they look like. They range in size from tiny spines to larger orbs. Thank you for solving the mystery! And so glad I haven’t caused irreparable damage. My daughter brought the two original plants home from college over 20 years ago, and I now oversee about 25 of their offspring (with others given away over the years). I have been watering once a week (Monday laundry, Tuesday plants, etc.), but that may be too frequent. I will be more careful and let the plants tell me when they are thirsty.

        Reply
        • My Garden Life

          You’re welcome Freddy! Sounds like you have your hands full. We’re glad we could help shed some light on what’s happening with your plants.

          Reply
  4. Kat

    Hi! Thank you for taking the time to write this awesome reference piece, and for answering others’ questions with such great detail!

    If you wouldn’t mind answering another… I haven’t had any luck on finding information about this weird, new addition to a few of my plants’ soil. I have two Calatheas that are seriously struggling with their recent move, and a Croton that I haven’t wanted to admit died from the same. Atop their soil are these funky semi-transparent, yellowish-brown, jelly-looking balls. None of my other plants have them. I don’t know where they came from, but I’m wondering if they’re some kind of egg. All of my plants are kept indoors in their own pots, and I don’t have the presence of slugs… any idea of what these could be?

    Thank you so much for your time!

    Reply
    • My Garden Life

      Hi Kat,
      At first we thought you might be referring to the remnants of slow-release fertilizer granules (balls) but the “jelly-like” description doesn’t jive with that, or the fact that they only recently appeared. What does fit your description is snail or slug eggs. We like this article from Plantophiles on Slug Eggs in Soil – What to Do When You Find Them? It describes the slug eggs and also offers solutions. Have a look and see if this might be the problem. You can also search online for images of slug eggs as a point of comparison. If your plants are in pots you might also consider doing an aggressive repotting – attempting to remove as much of the existing soil from the pot and around the roots as possible. Discard the all of the old soil and start with fresh, sanitized commercial potting mix. You’ll also want to sanitize your pots. However, unfortunately, there is zero guarantee that the slugs won’t return if you’re growing your plants outdoors. 🙁

      Reply
      • Kat

        Thank you so much for your response! I finally found an image of what I had discovered in my plants (https://www.torontomastergardeners.ca/askagardener/identification-of-round-eggs-on-soil-in-planters/). Assuming that the referenced article correctly identified it, it seems that your initial thought was correct. They were hard balls, not jelly-like as they had appeared, and gushed liquid when I squished them. I thought my new soil was infected with some kind of pest, but I’m thinking now that I was just naive. I appreciate the time you gave me; thank you again!

        Reply
        • My Garden Life

          Hello again Kat! Thank you for returning to share new information on the mystery balls in your soil. So glad to hear that your plant is not infested and the balls are simply slow-release fertilizer. I hadn’t considered that the balls swell with water, which could have given the impression that they suddenly appeared. Great detective work! 🙂

          Reply

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