Yep, thepink is on a good track

I use neem oil for just about every insect issue. Killed every knat within a few days.

It acts in a very strange way; insects don't copulate, the larve and insects don't eat, the eggs don't hatch and some insects forget that they can fly.

It interferes with the chemical signals used by insects and confuses them. The insects won't disappear straight away, they will starve to death etc.

Good luck with it. Oh, neem oil is harmless to the plant but in its pure form add only 5ml per 1 litre and also mix in 3 ml of soap to help the oil to mix well. Shake well !