Small Black Flies In Lemon Tree Compost.
If you have flies in the lemon tree compost a number of solutions are
possible to prevent this.
1. grow some seeds around the base of the pot this has a sent that will
stop the flies.
2. Drench the compost in the pot with a systemic insecticide such as Provado
3. Change the compost by re potting the lemons and using a soil based
John Innes compost.