Pests & Plants: Podcast Episode #33

Updated: Oct 11

As much as we all LOVE houseplants, pests are honestly inevitable. It shouldn't be something that discourages you and hopefully this will help you with any pest problem you have with your houseplants! In this blog & podcast we will talk about what the most common pests are, how to know whether or not you have them, and how to prevent and treat for them.


Spider Mites


What are they & what do they do? Spider Mites are tiny white, yellow, black or red mites that suck the sap from the new growth of your houseplants. These mites can rapidly reproduce in a short period of time so catching them early on is important for you plant's health. They are not harmful to people or pets.

How to know you have them:

  • They are so small that sometimes they are invisible to the naked eye! To check if they are spider mites, take a white piece of paper and press it against the back of the leaf. If there are tiny dots on the paper/tissue them you more than likely have spider mites.

  • Usually spider mites set up camp underneath leaves and form a very fine webbing similar to a spider's web. The web can cover both the leaves and stems so this is a good indication you have spider mites.

  • You may notice irregular discoloration in the leaves. There could be white or yellow blotches which are the symptoms of of the mite's damage.

  • Leaves may even seem wilted. Obviously this could be a sign of irregular watering but if your plant has been cared for properly and your leaves are still wilting, it could be an indication of spider mites.


Treatment: There are lots of things to try, so here is a list of them...

  • Trim off heavily infest leaves and stems (this should be in conjunction with other treatments).

  • Give your plant a shower or spray with water, which can dislodge many of the mites and the webs (this should be in conjunction with other treatments).

  • Spray with an insecticide (I recommend Insecticidal Soap) about once a week.

  • Use a water, oil, and soap mixture about once a week.

  • Here is what The Complete Houseplant Survival's Manual recommendations...1 tbsp/15 ml dishwashing liquid, 1tbsp/15 ml vegetable oil (canola or corn oil), 2 qt/2 l lukewarm water.

  • I have also seen people use Neem Oil instead of vegetable oil.

  • Using predatory mites could help if you have many plants with problems. I have not tried this solution before because I have been successful with other techniques. I, personally, don't want to go this route unless it is absolutely necessary. When researching, I found a couple products to recommend...

  • Predatory Mite Species for Spider Mite Control

  • Live Neoseiulus Amblyseius Cucumeris (these can also be used for prevention)

  • If all else fails, throwing away your plant may be the best solution. You don't want the mites to spread to all your other plants. Sadly, I have had to do this with a couple plants before.

Prevention: Hot, dry situations are where spider mites thrive. Allow for good air flow, increased humidity, and ensure you are continuously checking your plant to help prevent them to begin with.


Regularly cleaning your houseplant leaves is also a way to prevent spider mites from infesting the underside of leaves where you can't see them.


Giving your plant the care it needs can also help prevent spider mites. This is because weak plants are easier for pests to prey on.


Use a systemic insect control is also a solution to help prevent pests. This is applied to the plant soil and the plant takes it up. If pests that suck the sap out of houseplants feed on plant with a systemic insect control, they are also now feeding on toxic leaves and stems. This should kill them and prevent multiplication of this pest on your plant.


My Experience: These pests are my number one problem in my home. The ironic thing (and maybe the telling thing) is that the plants who have issues are all sitting in south windows. In those windows the temperature is warmer because of the direct or bright, indirect sunlight. The problem also arose at the tail end of winter when the house was very dry. I try to save my plants that have spider mites if I can help it. I constantly check my plants just in case so I can simply catch it early. I typically cut off the highly infested stems, place my plants in the shower then spray an insecticidal soap. I will repeat the shower and insecticidal soap about once a week until I am not seeing any evidence of the mites.


Mealy Bugs


What are they & what do they do? Mealy bugs look like little pieces of cotton that are stuck on your houseplant. These are also pests that suck the sap out of houseplants, similar to what spider mites do. They are not harmful to people or pets.

Mealy Bugs (Source: U of M Extension)

How to know you have them: If you see what looks like little white cotton on the leaves or stems, this is more than likely mealy bugs. These pests typically live in the nooks and crannies of the stems and leaves so it important to look thoroughly throughout the plant, not just the leaves.


Treatment: These pests produce a white coated material around their bodies and eggs which can actually prevent water or pesticides from harming them. The best way to treat mealy bugs is removing them by hand. Taking an old paint brush, makeup brush, or cotton swab and dipping it in rubbing alcohol to remove the pests from their corners is best. Once you have removed everything, I would recommend spraying insecticidal soap or a water, oil, and soap mixture as a precaution. I would repeat hand removing the pests and spraying insecticidal soap weekly until there is zero evidence of them anymore.

Mealy Bugs (Source: U of M Extension)

Prevention: Regularly cleaning your houseplant's leaves and stems is a way to prevent mealy bugs from infesting the nooks and crannies of your plant.


Giving your plant the care it needs can also help prevent mealy bugs. This is because weak plants are easier for pests to prey on.


Use a systemic insect control is also a solution to help prevent pests. This is applied to the plant soil and then the plant soaks it up. If pests that suck the sap out of houseplants feed on plants with a systemic insect control, they are also now feeding on toxic leaves and stems. This should kill them and prevent multiplication of this pest on your plant.


My Experience: Even though I have had the most problems with spider mites, mealy bugs are a close second. In my opinion, they are much harder to get rid of if they infest a plant with smaller leaves. For example, I bought a Prayer Plant from a nursery and at the time I didn't see an issue. After a few weeks, I saw mealy bugs collecting in the corners of the leaves. I tried cleaning it up but because there were so many nooks and crannies to clean out, it was hard to get all of them, so I ended up throwing it away. On the contrary, I had mealy bugs on my Monstera and this was VERY easy to clean since the leaves and stems were so big. There weren't many places for the bugs to hide.


Fungas Gnats


What are they & what do they do? These are annoying pests that look like tiny flies who crowd around your houseplants. One adult can lay up to 300 eggs at one time so these guys reproduce and grow fast. The larvae feed on the small roots, or any rotting parts of the plant, in the soil. If this isn't controlled, your plant may not grow to its fullest potential and may shed older leaves. They are a nuisance but not harmful to pets or people.

How to know you have them: This is usually pretty easy to spot. If you have little tiny bugs that fly into the air in and around your houseplants, this is probably fungus gnats. If you don't see anything freely flying, try disturbing the soil a bit to see if anything flies out.


Treatment: There are many things to try based on severity. Here are some options...

  • Fungus gnats thrive in moist soil so try allowing the soil to dry out completely before watering again. This could make it inhabitable for larvae and prevent adult fungus gnats from laying eggs in your soil.

  • If you have houseplants that needs to be consistently moist, try using yellow sticky traps. These will trap, and eventually kill, the adults which prevents eggs from being laid.

  • Using a soil drench could also be effective to kill off the larvae (here are a couple products I found on Amazon...Summit Responsible Solutions Mosquito Bits, goGnats and Root Cleaner). There are probably other brands but I saw several houseplant Instagram accounts using the Summit brand.

  • If it is REALLY bad, repotting your plant with new soil may be the best and only solution. Not only should you replace the soil, you should wash off all the soil from the roots system as well. This way you can be confident there aren't any lingering larvae attached to the root system.

Prevention: Some of the treatments methods double as prevention methods. Allowing AT LEAST the top couple inches of soil dry out between watering (depends on the type of plant) can absolutely prevent these bugs from laying eggs. If you are really worried about fungus gnats you can use the Mosquito Bites inside the soil to prevent any infestation from getting out of control.


My Experience: I haven't had many problems with fungus gnats because I allow my soil to completely dry out in between waterings with any plant that will let me. I noticed in spring, I repotted some Elephant Ear and Caladium bulbs with new soil and there were a few gnats flying around but I haven't seen any in about a month. I think this is simply because I keep my soil on the drier side.


Thrips


What are they & what do they do? Thrips are another insect that feeds on leaves and flowers. They look like tiny, thin, dark-colored bugs.

How to know you have them: You may see thrips jumping around your houseplants and moving along your leaves or flowers. Once you have an infestation of thrips, there may be silvery lines along the leaves where it sucked the sap from the plant. If the damage is bad, leaves may begin to curl and flowers may have dark splotches on them.


Treatment: Bringing your infested plants in the shower or spraying them with water can knock off any insect that is living on it. I would recommend doing this every few days until there aren't any left. If this isn't enough, you can use an insecticidal soap or water, oil, and a soap solution. Since these do jump around, using stick traps could help as well! Thrips are drawn to bright blue so make sure to buy blue instead of the commonly found yellow traps.


Prevention: Regularly cleaning your houseplant's leaves prevents thrips from infesting your plant. Giving your plant the care it needs can also help prevent thrips. This is because weak plants are easier for pests to prey on.


Use a systemic insect control is also a solution to help prevent pests. This is applied to the plant soil and the plant takes it up. If pests that suck the sap out of houseplants feed on plants with a systemic insect control, they are also now feeding on toxic leaves and stems. This should kill them and prevent multiplication of this pest on your plant.


Scale


What are they & what do they do? Scales are also plant sap sucking insects that attach to houseplants and rarely move from that singular spot. They are easy to spot as they get older because they look like they have a dark shell surrounding them.

How to know you have them: Typically you will find scales attached to stems of the undersides of leaves. They are most attracted to Ficus and Ferns but they are not limited to those two types. If you see a dark brown, grey or black round bug stuck to the stem or leaf, more than likely it is scale.


Treatment: The treatment may be as easy as taking a warm cloth with soap and water to remove each scale my hand. If it is a smaller plant you can use a cotton swab, paint brush, or makeup brush too. Repeating this about once a week until you do not see any evidence of more should be all you need! If you need something else to try, you can use an insecticidal soap or neem oil to help kill and remove scale.


Prevention: Regularly cleaning your houseplant's leaves prevents scale from infesting your plant. Giving your plant the care it needs can also help prevent thrips. This is because weak plants are easier for pests to prey on.


Use a systemic insect control is also a solution to help prevent pests. This is applied to the plant soil and the plant takes it up. If pests that suck the sap out of houseplants feed on plant with a systemic insect control, they are also now feeding on toxic leaves and stems. This should kill them and prevent multiplication of this pest on your plant.


Aphids


What are they & what do they do? These tiny yellowish, white insects are just another sap sucking insect that feeds on our houseplants!