Common Houseplant Pests
- how to identify and control bugs on indoor plants -

Posted on August 6, 2018

Common Houseplant Pests
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

mealy bugs on houseplant
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 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 minimise 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

Houseplant Pests - spider mites on houseplant
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.

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

Houseplant Pests - scale insects on houseplant
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.

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

Houseplant Pests - fungus gnats on houseplant
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.

Fungus Gnats on 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.

Aphids

Houseplant Pests - aphids on houseplant
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.

Aphids on 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

Houseplant Pests - thrips on houseplant
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.

Thrips on 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

Houseplant Pests - whiteflies on houseplant
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.

Whiteflies on 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

Houseplant Pests - roach on houseplant
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.

Roaches on Houseplants - What to do

Allow 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:
  • 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 insect 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.

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.



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Fruit Flies

Fruit fly
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.

Fluoride Damage

fluoride damage
Many sources of public water contain fluoride. Fluoride is good for people's teeth, but not for 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 caused by fluoride should not be confused with insect damage. Watering with distilled, rain, or filtered water will prevent your plants from developing this condition.


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