Thrips on houseplants – how to combat them at home?

Diseases and pests

Various pests cause serious damage to plants. Thrips appear on houseplants suddenly, forcing gardeners to immediately search for detailed information about the pests, study their appearance in photographs, and ask themselves how to deal with them, as without adequate measures, the plant will quickly die.

Thrips (also known as bladder-legged thrips) are a large group of insects, most species of which cause significant damage to agricultural crops and various houseplants. More than 300 species of these pests are common in our country.

Plant damage by different types of thrips

The pest's body is elongated, up to 2 mm, and its coloration varies (usually inconspicuous—light yellow, dark brown, or black). Adults have two pairs of narrow wings with long hairs. The length of the wings varies depending on the species; some are absent. The head has antennae consisting of segments (an average of 9 segments). The mouthparts are piercing and sucking. The light yellow larvae are no larger than 1 mm.

Mature individuals move very quickly thanks to three pairs of legs located in the thoracic region. Each leg has one tooth and one bladder-like suction device.

They reproduce rapidly, capable of doubling their population size in 4-6 days. Eggs are laid in flowers and leaf tissue. The offspring hatch after 10 days. The larva develops into an adult insect in 1-2 months. Due to this short development cycle, some species produce several broods throughout the year.

These pests exhibit social behavior. Like ants and termites, they cooperatively guard their eggs. Besides sucking sap, thrips transmit a variety of viruses harmful to plants.

It is quite difficult to identify a specific species, since the parasites are small and their species variability is widespread.

Common types of thrips that harm ornamental plants:

Name	Body length	Color	What's amazing
Western flower or California flower	0.9-1.2 mm	From pale yellow to dark brown. The bristles on the body are dark, the wings are light yellow	Carnations, gerberas, gypsophilas, pelargoniums, roses, Saintpaulias, chrysanthemums, cyclamens, and cinerarias
Tobacco	0.8-1.2 mm	Females are light yellow, sometimes dark, with grayish antennae and legs, and yellowish wings, occasionally light gray-yellow. Males are slightly lighter in color.	Solanaceae, Apiaceae, Ranunculaceae, Rosaceae and Liliaceae
Decorative	1.1-1.7 mm	The female is yellow, then turns brown and black. The wings are darkish, with light spots at the base and tips of the wings. The males are lighter.	It causes particularly severe damage to crassulas (money trees), orchids, and palms. This pest can also destroy monsteras and dieffenbachias.
Bulbous	1-2 mm	Dark brown	Common onions, as well as onion scales from various types of lily plants
Roseanny	Up to 1 mm	Brown	Flowers of rose-colored plants and some other plants
Palm	0.8–1.4 mm	Bright yellow, almost transparent, with blackish bristles. The head and legs are light yellow.	Solanaceae, various types of orchids
Dracaena	About 1 mm	Yellow-brown	Dracaenas, hibiscus and ficus
Polyphagous	About 1 mm	Dark brown	Flowers and ovaries of ornamental plants

How to recognize a parasite infestation

Thrips themselves aren't always immediately detectable. They're quite secretive and prefer to infest individual plants, gradually moving on to others.

The discoloration of some leaves should raise the gardener's suspicion. Also, in flowering plants, pollen is intensely shed from the stamens onto the petals (this phenomenon can also be observed during hot weather and as a result of a spider mite attack).

If, upon inspection, many small punctures are found (like from a needle on fabric), then this means that they were made by thrips, which means that they drank the juice from the plant.

Brownish or russet spots may be visible on the underside of leaf blades. These are damaged areas. When oxygen enters the plant cells, they often take on a silvery tint. You may also notice a sticky residue and brown-black dots (thrips excrement) on the leaf, which contribute to the development of sooty mold.

A late sign of a thrips attack (if no measures have been taken to save the plant) is the falling of leaves and flowers, as well as the curvature of the trunk.

Home and chemical methods of control

First of all, it is necessary to isolate the flower infested with thrips, replace the surface layer of soil and treat the area where the flower pot was previously located with a soap-alcohol solution.

Remember!

The container must be moved carefully to prevent the parasites from spilling out and then migrating to neighboring plants.

Next, taking into account the extent of the damage, you can choose the methods of control.

Chemicals

Although manufacturers offer many effective chemical treatments, not all of them will help get rid of the pest. There are several reasons:

thrips hide in places that are difficult for sprayed substances to penetrate;
females lay eggs inside plant tissues;
pupae often end up in the soil;
Eggs and nymphs have a protective cover that protects them from the effects of contact insecticides (they are best used on ornamental foliage plants and various flowering species, but before the budding phase).

You can use:

Akarin and Fitoverm (toxicity class VI - low hazard for humans and animals);
Aktara, Inta-Vir, Confidor Extra, Tanrek, Spintor, Agravertin, Karate, Bankol and Karbofos (class III - moderately hazardous);
Actellic and Vertimek (Class II – highly hazardous).

The last two agents are particularly toxic, and Karbofos has a very strong and unpleasant odor. Therefore, treatment should only be carried out outdoors. It is recommended to first use the more environmentally friendly biopreparation Fitoverm, and then the growth stimulator Epin.

Before applying any insecticide, wash the plant under a warm shower. When using insecticides, wear personal protective equipment and carefully read the manufacturer's instructions and recommendations.

Number of treatments	Average daily air temperature	Interval between treatments
3-4 (for very toxic ones, for example, Actellic, 2-3 is enough)	25-28°C	5-6 days
	21-24°C	7-8 days
	15-20°C	10-12 days

Spraying with preparations at temperatures below 18°C is ineffective. The optimal temperature range is 20-26°C. It's best to perform the operation before midday and avoid exposing the leaves, which are still wet from the chemicals, to direct sunlight. Otherwise, the plant will be burned, and the pesticide components will be destroyed by ultraviolet light. Ventilate the area well.

With improvised means

In the initial stages of a plant infestation, you can try to get rid of it using folk remedies. For example:

Dilute 15-17 g of liquid soap in 1 liter of warm water, spray the plants with the resulting soapy solution and cover them with a plastic bag for 2-3 hours, then wash;
Infuse 1 teaspoon of chopped onion or garlic in 1 liter of water, use after 24 hours;
fill a 1 liter jar with dried marigold flowers and pour 0.5 liters of water into it, leave for 2 days, then strain and use;
chop 40-50 g of dry tomato leaves, pour water over them and leave for 2-3 hours, then strain and dilute with 1 liter of water;
Pour 50 g of dandelion leaves or roots with 1 liter of warm water and leave for 3-4 hours, then strain and treat the flowers;
pour 100 g of chamomile and leave for ½ day, then add 5 g of green soap, spray the plants, and after 1 day wash off with warm water;
Pour 0.5 cups of crushed tobacco into 1 liter of water and leave for 1 day, strain, add another 1 liter of water and use;
50 g of freshly picked celandine in the flowering phase or 100 g of dry celandine, leave in 1 liter of water for 1 day, strain, and then spray;
fill a compact container with crushed garlic or turpentine, place it in a flower pot and cover everything with a plastic bag for 3 hours;
dilute 1 teaspoon of mustard in 1 liter of water, use the liquid to water the soil (against pupated larvae).

All this can be used in the morning and evening.

Prevention

Each purchased plant should be thoroughly inspected, and once it's home, it should be quarantined for 2-3 weeks. Preventative treatment with an insecticide can be used. Regular inspection (preferably with a magnifying glass) should be performed, with particular attention to the undersides of the leaves.

Please note!

Thrips thrive in dry air, so it's important to maintain optimal humidity in the room. It's a good idea to give the plants a warm shower periodically, mist them daily, or wipe the leaves every five days.

Sticky traps of blue or yellow color hung around the perimeter will help to quickly detect the pest.

Gifted and purchased flower bouquets are a common source of thrips. It is recommended to place them away from houseplants.

Affected buds, flowers, and inflorescences should be removed without hesitation. If the plant has been infested, the top layer of soil should be replaced and the pot area thoroughly cleaned.

Frequently Asked Questions

Is it possible to get rid of thrips by washing the plant under a hot shower?

A hot shower helps somewhat, but it doesn't completely eliminate thrips. Furthermore, not all plant species can withstand this treatment.

Is it possible to kill thrips the first time?

It's not always possible to eliminate the pest in a single treatment, as a new generation of pests hatch from the eggs laid. Therefore, multiple treatments are recommended.

Is it possible to combine medications with folk remedies?

Yes. For example, green soap has insecticidal properties and, when combined with other products, can achieve good results. When using chemicals, be sure to carefully read the instructions.

Are thrips dangerous to humans or pets?

These parasites are harmless to humans and their pets. They can only cause discomfort if they get into the eyes or respiratory tract.

Gardeners strive to get rid of pests on their houseplants as quickly as possible. This is absolutely right, as thrips quickly destroy their green plants by sucking their lifeblood. But to ensure this is successful and prevents recurrence, it's necessary to use effective products and methods, taking into account the recommendations above.