Don't Set Your Plants on Fire: How to Treat Thrips
Image by @jensgreenhouse
Ah thrips, the glitter of the plant world: Pervasive, persistent, positively peevish. These little guys are perhaps the most challenging pests to tackle, but can be managed with some effort.
What are thrips?
Thrips are little cream-coloured or black sucking insects. They are very tiny, so tiny you often will notice the signs of their damage before you notice the insects themselves. Look for dull or dirty looking leaves and new growth that is deformed. The undersides of leaves and new growth are the most tender parts of a plant, so that is likely where you can see them.
How do they get here?
The answer, my friend, is quite literally blowing in the wind. Thrips have wings but are terrible fliers, so they coast through the air on the breeze. This means they can hitch a ride on clothing or even enter through a window screen. It is more common in warmer climates as they cannot survive our winters. Thrips are often brought into our homes through flower bouquets or even on fruit and vegetables. We are so careful to check new houseplants for pests before we buy them, but most people never even consider that a flower bouquet could be a Trojan Horse filled with pests!
Why are they so difficult to treat?
Thrips have 3 stages to their life cycle, and knowing about this will help to understand how difficult it can be to treat them. Thrips lay their eggs in the tissue of leaves. They hatch into nymphs after 3 to 5 days. The nymphs become adults in another week and adult thrips live for about a month. They can reproduce sexually or asexually, meaning that one is enough to create a big population. And they breed quickly, so treat them as soon as you notice them!
How to Treat Thrips:
Step 1: Isolate your plant. Because they can rapidly spread from plant to plant, move the affected plant. Assume that the plants near the affected plant also have thrips and preemptively treat them too.
Step 2. Put your plant in the shower or sink and spray it down with lukewarm water. Gently lather it with Dawn dish soap (it’s gentle) or an insecticidal soap. Be sure to get the undersides of leaves and the stems. Leave the soap on for 30 minutes or so and then rinse off with lukewarm water.
Step 3. Use an insecticidal spray like Safer's End-All or Safer's 3-in-1. This is a great option for larger plants that cannot be moved to the shower and washed down. Insecticidal sprays only kill thrips that have hatched, not the eggs that are safely buried inside the leaf, so you will need to spray the plant every 3 to 4 days as new thrips emerge. One single treatment will not eliminate them.
You will never understand the hyper vigilance of prevention if you have never encountered thrips. But for the sake of your plant care knowledge, here's what you should do:
- Check bouquets and keep them away from plants.
- Inspect plants before you buy them and bring them home.
- Quarantine new plants for 3 to 4 days (length eggs take to hatch) before you mix them in with your collection.
- Make inspecting your house plants part of your daily routine. Have insecticidal products on hand before you need them.
Remember there is no shame in tossing out a plant that you are unable or unwilling to treat for pests. Just bear in mind that thrips spread very quickly, so take action as soon as possible!