This is definitely an insect problem but I cannot tell what kind they are.
Pyrethrum is usually distributed as a dust. If you have purchased a white powder there are better ways to control the problem.
- Take a cloth or paper towel and soak in a solution of 5 ml dish soap to 1 liter of water.
- Then wipe all the leaves of the plant so you are covering the top and bottom of all the leaves.
- Repeat at least twice every five to six days to catch the next generation of the pest when they hatch
Soap and water will kill most insects and will not put dust into the air. If you have other plants you should inspect them closely to see if they have the same problem and treat them too.