I have a window box with my herbs in and lately I have noticed black aphids on my chives (and a few on my coriander). There are so many on my chives, that they are all turning yellow and dying. Can anyone suggest a way to get rid of them, yet still making the chives OK to eat ???? I have read that soapy water will help - but I dont really want to eat chives with detergent on them !!!!