Bugs in my houseplant..?

Question:I've heard a couple of times now that you can spray water and dishsoap on your plants to kill bugs. My question is, how much soap, how much water and how wet do you need to get the soil? At this point bugs are only in the soil not on the plant. It's a Peace Lily and it is a medium size. Thank you.

Answers:
I usually use 1 part dish soap to three parts water, it has worked good so far.