How to get rid of thrips

Are your indoor growing invaded by thrips and you are looking for safe, effective and natural remedies to eliminate them? This guide from Grow Shop Italia is designed to help you prevent the appearance of these small and annoying insects.

If you have noticed small winged insects on your plants, be careful as they could be thrips of plants. These are tiny parasites that are quite common in both indoor and outdoor growing.

Difficult to eliminate and not always easy to recognize, they can be highly harmful to plants .

Almost all herbaceous plants are attacked , but also vegetable plants - such as tomatoes (in fact we speak of tomato thrips) - flowers and fruit (for example citrus fruits). Among the most affected plants, however, there are hemp and cotton , but also plants in protected cultivation or grown inside a greenhouse during the cold season.

Home growing is a very rewarding hobby. But how frustrating is it for a grower to realize that plants cared for with so much passion and attention have become the favorite food of harmful parasites? So much so, we imagine.

This is why in this manual we will try to understand more about thrips by illustrating all the most effective remedies to keep them as far away from your crops as possible.

What you will find in this guide:

• let’s know the thrips of plant
• Thrips: which house and vegetable plants do they affect?
• Life cycle and thrips control
• Thrips of plant: damage and remedy
• How to prevent and control thrips
• Bio or chemical remedies: how to get rid of thrips

Keep reading.

let’s know the thrips of plant

Whether it's olive thrips, citrus fruits or other plant species, it doesn't matter. What you need to know is that these tiny insects, almost invisible to the naked eye, are a serious threat to all growers.

Before explaining how to get rid of them, we want to help you first understand what they are and how you can recognize them.

As we have already told you, thrips are tiny parasites belonging to the Thysanoptera insect family .

There are several species of these feared insects, the most important in the agronomic field are: 

• Frankliniella Occidentalis;
• Thrips tabacii;
• Echinothrips americanus;
• Thrips setosus. 

Among these, the one capable of causing the most serious damage to crops is Frankliniella Occidentalis (Western flower thrips). 

It is an insect native to California, introduced into Europe, specifically in Holland, in the mid-1980s, causing great damage to cotton crops. 

Like many other species of parasites, these are also phytomyceous insects , that is, species that attack the leaves of the plant and feed on their lifeblood.

This explains why they represent a big problem for all growers, especially those dedicated to greenhouse and indoor cultivation.

Before focusing on the fight against thrips and the natural remedies to eliminate them, find out which plants are most subject to the annoying attentions of these parasites.

Thrips: which house and vegetable plants do they affect?

Cannabis is among the plant species that thrips are particularly fond of as are cotton plants. However, these tiny and very dangerous insects like many other species, not only grown outdoors, but also those protected in domestic crops or greenhouses.

Among the so-called horticultural plants (i.e. vegetable gardens), the most affected are:

• Solanaceae;
• Liliaceae;
• Legumes;
• Cucurbitaceae;
• Composite.

Among the flowers, however, you need to pay attention to those of: 

• Chrysanthemum;
• Geranium;
• Saintpaulia;
• Carnation;
• Rose;
• Cyclamen;
• Orchid;
• Poinsettia. 

Regarding fruit trees, the most damaged are citrus and peach trees, olive trees, plum trees, cherry trees, almond trees (Drupaceae), but also apple and pear trees (Pome fruit).

For a grower, finding thrips on plants can be very discouraging. These insects multiply very quickly - especially when temperatures are high - and can fly and move easily from one plant to another, causing serious damage.

But do not worry! By learning all about their life cycle and the signs to look out for you will be able to eliminate them as quickly as possible. Provided, however, that the most effective natural remedies are used on thrips.

Life cycle and thrips control

These plant parasites are very difficult to recognize with the naked eye, because they are so tiny. Depending on the species, the body can vary in color. 

They are generally light, between white and green-brown. Looking at them with a magnifying glass it is possible to clearly see the tapered body and the stinger-shaped mouth

They have an elongated shape, with their wings folded over their backs when at rest. The dimensions are really small:

• Females are 1.2 mm;
• The males, smaller, measure 0.9 mm.

Generally they take refuge on the underside of the leaves or in the flower buds and for this reason it is not easy to find them. But you just need to pay attention to some signs to be able to notice their presence. Among these are:

1. Whitish streaks of saliva on the leaf, similar to snail slime;
2. Dark drops of dung on the leaves;
3. White specks or "discolorations" of the leaf tissue as the parasite proliferates.

In fact, the thrips scratches the surface of the leaf to suck the chlorophyll, revealing white specks. Its action, in fact, significantly slows down the normal chlorophyll photosynthesis activity of the leaves, which in the advanced stage turn yellow and die.

Thrips eggs are laid by the female on the leaves, petals and stems, via a saw-shaped ovipositor that cuts into the plant tissue causing further damage to the plants.

The eggs then fall to the ground and begin to hatch when temperatures are optimal (approximately between 26°C and 28°C).

Temperature has a major impact on the life cycle of these insects. In winter, in fact, thrips hibernate ready to proliferate with temperatures between 15 and 30 °C . In fact, the period of greatest activity is spring and summer , where it can reproduce for up to 7 generations. In the greenhouse, however, it survives even in the colder months, thanks to the artificial climate which keeps the temperature constant.

It is very important to immediately notice the infestation of this insect. But how can you recognize and identify these tiny insects before they irreparably damage your plants? Find out by reading the next paragraph.

Thrips of plant: damage and remedy

Adult insects feed mainly on flowers, but also on stems and leaves, damaging the plant with their bites. Obviously, the most affected are the leaves which are cut, perforated and scraped to get to the sap on which these insects feed.

Learning to recognize plant damage is the first step if you want to successfully eliminate thrips from your crops.

Damage to vegetation following the trophic feeding bites and oviposition activity of these insects can occur in various ways. 

1. Sucking stings on stems, flowers, open petals and leaves;
2. Discoloration of the plant;
3. Deformation of fruits, buds and flower heads;
4. Necrotic plaques; 
5. Small white or silvery spots on the tubular-shaped leaves, between 1 and 2 millimeters wide.

All these reactions are mainly due to the toxic substances present in the saliva of the thysanoptera insect. Although it is not a very aggressive parasite - in the sense that it is very rare for the plant to die - a thrips infestation can cause a significant reduction in final production.

In fact, following the feeding activity of these parasites, necrotic, silver-colored areas may appear on the plant, which actually compromise the plant's ability to photosynthesize. This can therefore, for example, stop the development of shoots, reducing the final yield. 

In addition to direct damage, the thrips insect can also be the cause of indirect damage , as it is a vector of viruses dangerous for some plants, such as:

• Impatiens Necrotic Spot Virus (INSV);
• Chrysanthemum stem necrosis virus (CSNV);
• Tomato Chlorotic Spot Virus (TCSV);
• Tomato Spotted Wilt Virus (TSWV).

Additionally, the cuts that parasites cause can encourage the spread of bacterial and fungal infections, such as botrytis .

All this makes it essential to prevent the problem before it is too late for the plant. In the next paragraphs we will therefore focus on all the activities you can carry out to prevent and eliminate thrips from your crops.

How to prevent and control thrips

As often happens in agriculture, the best method to keep this and other parasites away from your plants is prevention . 

To defend against attacks and prevent uncontrolled spread, the first step to take consists of careful and constant control and monitoring activities , 

accompanied by a whole series of actions that can help you prevent thysanoptera from colonizing your crops.

What should you do if you want to keep thrips away from your plants?

1. Keep the cultivation environment clean , especially the indoor one;
2. Disinfect all environments and equipment used for cultivation daily;
3. Place yellow or blue anti-thrips chromotropic adhesive traps in external or internal cultivation environments: it will warn you at the first signs of contamination;
4. Launch antagonistic predatory insects such as ladybugs, Orius Laevigatus, Amblyseius cucumeris and the like, which are able to take root well even in greenhouse and indoor environments and which feed on these parasites, causing real feasts;
5. Use entomopathogenic nematodes (in particular Steinenernema feltiae) , i.e. microorganisms capable of parasitizing the larvae of various insect species and, therefore, preventing development into adult forms.

Those just illustrated are, obviously, biological defense methods . Where the infestation is more serious it will be advisable to use a specific chemical or natural insecticide product for thrips . Let's see which are the most effective in the next paragraph.