Assuming your herbs are in the ground a sharp blast from the hose may well remove most of the bugs.

If not, spray them thoroughly with an organic soap solution, and be prepared to wash the herbs thoroughly before using them.

Hum I wouldn't want to use herbs sprayed with anything even if it were organic Tugb.

I'll admit that the kind of washing you have to do afterwards is almost enough to make you go to the nearest organic grocery store. That's why I prefer to dose my herbs well with ladybird beetles in the spring--too late for that now, though.

perhaps a solution of water and vinegar should do the trick. As lemon balm likes a bit of acidity it shouldnt cause any problem, thats what i use on my cabbages and basil.

Although I don't have any lemon balm to test it on at the moment as my seeds don't seem to want to start.

The trouble with that, Prince_medic, is that vinegar is very good at killing foliage in surprisingly small doses. It might be hard to find a dose that bothers the aphids without bothering the plants.