Handpick or use grey water from your dishes. Look carefully at the outside bottom, this is prime bugland. Carpenters can move into the base of the pot through drainage holes. If the problem is critical, repot. I wouldn't bother with chemicals as they expensive, dangerous and unnecessary, but that's just me(and a large crew of other enlightened growers).
Are they actually grubs? These are the larva of beetles and are pretty juicy looking compared to say maggots (uncomposted organics in soil) or moth larva (on leaves). Identifying a specific pest really helps in figuring out the best way to deal with it. Good luck.