Thrips can results in different types of damage to your plant. This depends both on the plant species and the type of thrips.
Key thrips damage symptoms
Sunken streaks and patches – leaves and stems
Colored spots or patches – usually silver-white
Stunted growth – buds (flower and leaf)
Often combined with – plant virus, fungal diseases
Read on to discover what type of problems thrips cause on plants. Included are images of thrips damage on fruit trees, flowers, and trees/shrubs. Damage can appear on leaves, stems, buds, fruits and flowers. You’ll get a good idea of what thrips damage looks like!
What parts of plants do thrips attack?
Usually, soft, young tissue is attacked first.
Also, buds, junctions and bends that are protected from wind, rain and predators are colonized early on.
Some species of thrips even attack roots underground.
- Not all thrips are bad, however. There are some beneficial thrips that help eat up other pests and fungus!
- Learn more about the various thrips species
Damage to the whole plant
- Shake a leaf over a sheet of white paper.
- Tiny specks will fall down on it.
- If they’re a bit oval and long, shaped like a small grain of rice, they’re thrips!
- They come in different colors, but usually brown, gray or yellow.
The main symptoms of a thrips infestation on a plant are the following:
- leaves with spots that are silver-white or yellow, then turn to brown or rusty-red
- leaf losing its thickness
- as the entire leaf is infected, it curls up
- leaf drop is rare
In some cases, thrips will trigger leaf galls (usually as part of the nesting/egg-laying process).
Damage to leaves
Typically, portions of leaves are flattened and aren’t as thick as the rest of the leaves.
- This is because thrips feed on the content of cells. Like mosquitoes, they drill beneath the surface or skin of the plant. Thrips release enzymes that break down the inside of the plant into a nutrient-rich soup. Afterwards, they suck the content up. This flattens the leaf in the area.
Other telltale symptoms on leaves are that these spots often turn a silvery-white color. This may turn brown in time.
- Thrips feeding spots turn white because the space below is hollowed-out. Contents like green chlorophyll are sucked out.
- The skin and walls between groups of cells remain intact though. They form a kind of window that lets light through!
- The botanical term is skeletonization – only the skeleton or structure of the plant leaf is left.
Patterns of damage are more like short burrows or trenches dug into the leaf and young stem.
- They aren’t as long and twisted as leaf-miner damage, though.
- As an individual or a colony advances, this can either resemble a line or a widening spot.
Black dots or tiny pellets are actually what’s left after thrips have digested everything. It’s their poo!
- These black dots look a lot like the pycnidia spore-sacs on a plant that is suffering from leaf septoria.
Thrips egg-laying and larvae damage
Lastly, depending on which species of thrips is attacking your plant, you may find damage due to “thrips nesting“.
- As part of the thrips lifecycle, the female will lay eggs in a cut or on a leaf or stem.
- These eggs hatch and the larvae secrete special chemicals to the plant around them.
- These chemicals disrupt neighboring cells, making it easier for thrips to feed.
- Sometimes the damaged cells proliferate and form galls.
Symptoms of thrips on stems
On stems and on leaf veins, the damage has the same causes but may look a bit different.
Thrips feeding damage on stems
- There are still trench-like structures where the thrips are feeding.
- Usually the color is brown instead of silver-white.
Thrips nesting in stems
- Egg-nests resemble dots that are white or light in color.
- These spots are the size of the prick of a needle.
- Learn more about thrips eggs and what they look like.
Symptoms of thrips on flowers and fruits
- The skin will also turn silvery-white. This is the cause for “silver banana” disease.
- Citrus fruits are also vulnerable to this. The skin is marked with white-gray patterns.
It’s still perfectly safe to eat the fruits, though.
- Shown here is thrips on a young orange tree fruit.
Usually, these thrips simply feed on the pollen and also help pollinate the plant. However, sometimes, they also attack flower petals.
- Damaged wet spots or discolored blotches appear on petals, similar to when you crease or fold them.
- Flower buds may stunt and grow deformed if too many thrips are present.
- Shown here, thrips on fairy-like aster flowers.
Diseases and pests that look like thrips damage
How to tell Septoria damage and thrips damage apart
Mentioned above is Septoria, a fungus that infects many different types of plants.
- Both have black spots, but those of Septoria are clustered together. They’re on the oldest spots. These spore-sacs don’t move when you rub your finger along.
- Oppositely, black dots of thrips are their waste. They’re distributed more randomly, not only on the spots. They’ll fall off if rubbed or shaken.
Lastly, both Septoria and thrips result in flattened leaf portions.
- However, edges around Septoria spots seem to swell and appear colored. This is because the plant is fighting the fungus back with an inflammation.
- With thrips, portions of leaves that touch flattened spots seem very healthy. There is no swelling or change in color.
Another check you can do is verify whether your plant is prone to septoria infection or not:
Other small insects that attack plants
About the same size as thrips is the red spider mite. However, its bright red color gives it away: not many thrips species are as red as it!
Smart tip about thrips damage
As with most pests, take time every week to walk around the house or garden simply to admire your plants. Not only will this lift your mood, it will reveal thrips infestations while they’re still small and easy to treat!
Credits for images shared to Nature & Garden (all edits by Gaspard Lorthiois):
Mango with thrips damage by Scot Nelson ☆ under Public Domain
Ficus thrips damage by Kim & Forest Starr under © CC BY 4.0
Thrips damage on leaf by Scot Nelson ☆ under Public Domain
Thrips on flowers by Robert Webster under © CC BY-SA 4.0
Fruit damaged by thrips by HeberM under © CC BY-SA 3.0