Hi

I recently posted about a pest that was infesting my chervil (and now my chives). Here's the description:

They are small (approx 1mm) black beetle type things - with a body the shape of a teardrop. 6 legs - 2 antennae. When you squash one they are a purple colour.

After a bit of research I think these might be Onion Aphids.

Can anyone tell me a good way to get rid of them?

I tried weak washing up detergent but that didn't seem to bother them.

I tried taking a photo but couldn't zoom close enough for the bug to be obvious.