I have a plant that I separated from the rest of the flowers and plants for the aphids. This aphid is very weird. Every week, I clean the substrate under water and cotton from aphids. But again the aphids are found. First, the black dots appear below the leaves Then the black dots become insect. And the leaves begin to pierce. Please help me if you know how to deal with this pest.
These are thrip. The adults are black and the size of an exclamation mark. The larvae live inside the leaf and produce the silvery mottling that you see on the leaves. The adults will produce black frass which you can sometimes see on the leaves as well. When the adults get crowded or the leaves are disturbed they will fly off to a new plant and start the cycle again.
I have never been able to control these insects due to:
- larvae cannot be controlled by soap and water as they are inside the leaf
- adults have wings and fly when disturbed to spread the problem
- they eat a wide variety of interior houseplants
At one interiorscape I saw a systemic pesticide used when they were still legal for indoor use but it was so toxic it killed the plants as well and smelled quite strongly.
I recommend bagging the plant and putting it in the garbage. Examine any other plants for signs of thrips and do the same.