How to Identify and Eliminate Thrips on Your Houseplants

Thrips is a houseplant pest that should always be taken seriously. They have the ability to infest a plant at a rapid pace and will cause very serious damage in the process. It is one of the few pests (along with spider mites) that I have had to throw away a plant because I just couldn’t fight them off.

Thankfully, since the early days of losing plants to pests, I am able to control them and save my plant the vast majority of the time.

Today’s blog post will be all about how to get rid of thrips, one of the worst pests, from your houseplants.

Featured Image taken by: Smartse, “A photograph of the leaves of a coffee tree that are curled, seen in Rwanda”, Source Link

Table of Contents

What are thrips and what do they look like?

Thrips are tiny insects that have slim bodies similar in shape to a grain of rice, except they are much smaller than rice. They are most often white, yellow, or brownish in color.

Whitney Cranshaw, Colorado State University, Source Linked Here

The name “thrips” refers to both a single insect and to a group of these insects.

Thrips suck sap out of a plant, damaging the plant in the process. They can also carry viruses, which they can pass during the feeding process from plant to plant.

Thrips reach the adult stage after about 2 weeks. Once mature, females can lay eggs daily. These eggs will hatch within 3 to 4 days, allowing thrips to develop into a large infestation in a short amount of time.

Whitney Cranshaw, Colorado State University, Bugwood.org, Source Linked Here

Signs your plant might have thrips

  • Tiny, rice-like flecks on your plant that are barely noticeable to the naked eye
  • Mature plant growth may become deformed
  • Foliage has tiny, discolored spots (or stippling) from thrips feeding on the plant
  • Feeding damage can also cause leaves to develop a silvery appearance
  • New growth emerges wonky, twisted, or deformed
  • Tiny black specs on leaf surface, which is waste left behind by thrips

It helps to use a magnifying glass to get a closer look at what is happening on the plant.

I will add a link to Amazon for the magnifying glass that I use and love. Not only is it high-powered to see tiny bugs, but it also has a light that you can turn on to help see things more clearly. I bought it in the summer of 2019 and it still works beautifully.

30x Handheld Magnifier with 12 LED Lights (linked to Amazon through the affiliate program).

An example of stippling or tiny blemishes on the leaf surface:

Whitney Cranshaw, Colorado State University, Bugwood.org, Source Linked Here

An example of the silvery appearance as a result of thrips damage:

Howard F. Schultz, Colorado State University, Bugwood.org, Source Linked Here

Here you can see both the thrips themselves and the deformed petals of the flower:

Metin GULESCI, Leaf Tobacco, Bugwood.org, Source Linked Here

Another closeup of stippling:

Whitney Cranshaw, Colorado State University, Bugwood.org, Source Linked Here

An example of deformed growth due to thrips:

John C. French Sr., Retired, Universities: Auburn, GA, Clemson and U of MO, Bugwood.org, Source Linked Here

How to control thrips?

Ensure plants receive adequate watering

Both thrips and spider mites will target plants that are super dry from underwatering or lack of humidity.

Water your plant regularly to prevent it from suffering in super dry conditions.

Give plants regular showers

Simply showering off your plant in the sink can wash off a good number of pests that are attempting to make your plant their home.

Showering your plant will also remove dust (or any other debris) from the leaves, allowing the leaves to photosynthesize at full capacity.

Use an insecticidal spray to help control them

Make sure to thoroughly coat your plant with whatever spray you choose to use.

The plant will also need to be sprayed a few times over the course of a couple weeks to continually eliminate new generations and those who may have slipped through the previous spray.

Here are the spray options that work for me:

  1. Neem Oil and Soap, Homemade Spray
    • Mix 17 ounces water, .5 tsp neem oil, and .75 tsp mild dish soap in a spray bottle.
    • Test on a small portion of plant first to make sure it will tolerate the spray. Some plants are sensitive
    • Link to Amazon for the Neem Oil I prefer to use
    • Link to Amazon for the Mild Dish Soap I prefer to use
    • Link to Amazon for the Glass Spray Bottles I use
  2. Rubbing Alcohol and Soap, Homemade Spray
    • Mix 4 ounces rubbing alcohol, 1.5 tsp mild dish soap, and 16 ounces water in a spray bottle.
  3. Purchase a Premade Insecticidal Soap
  4. Purchase a Spinosad Spray

Use Biological Control / Beneficial Insects

Some examples of beneficial insects that have worked for me (and will happily eat thrips) are:

  • Minute Pirate Bugs
  • Amblyseius cucumeris (predator mites)
  • Green Lacewings
  • Ladybugs

Beneficial insects can be purchased online for shipment directly to your house. You can release them as often as you’d like. I am releasing insects a few times a year when the weather is changing from season to season and pests are more likely to spring up.

Minute Pirate Bug, Photo by: sbushes, Source Linked Here

Important Side Note:

Beneficial insects make a huge difference in the amount of pests you will have to deal with when you have a large houseplant collection.

However, they may not eliminate every pest, so make sure to look over your plants regularly still. I learned this lesson the hard way. 🙂

I do not recommend using a systemic pesticide for this particular pest.

  • Systemic Pesticides are dangerous to everyone, not just the pest, because you’ve created a toxic plant
  • Many thrips are immune to pesticides now (read more about this below)

Because thrips have developed resistance to most registered pesticides, biological control is now the primary strategy for controlling thrips in greenhouse crop production. Biological control agents include predatory mites such as:

Neoseiulus (= Amblyseius) cucumeris
– Amblyseius swirskii
– Iphesius (= Amblyseius) degenerans
– Stratiolaelaps scimitus (= Hypoaspis miles)
– Gaeolaelaps gillespiei
– Gaeolaelaps aculeifer (= Hypoaspis aculeifer)

– Minute Pirate Bugs (Orius insidiosus)
– Nematodes (Steinernema feltiae)
– Fungal Insect Pathogen (Beauveria bassiana)

From the Ontario Ministry of Agriculture, Food, and Rural Affairs, Thrips in Greenhouse Crops – Biology, Damage and Management, Source Link

Will thrips spread to nearby plants?

Yes, they are very good at moving from one plant to another. Thrips can crawl or use their adult wings to fly short distances to other plants. And, because they are so small, a light breeze or gust of air can carry them to other plants.

Resources:

http://www.omafra.gov.on.ca/english/crops/facts/14-001.htm

https://content.ces.ncsu.edu/insect-and-related-pests-of-flowers-and-foliage-plants/thrips-found-on-flowers-and-foliage

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