Poison will also kill the plant. BUT, here's a little trick of the trade, so to speak:
1). Shake off as many worms that you can.
2). Take some 1/2" wide cellophane tape (clear tape) and wrap your plant around the stem with the sticky side out.
3). Check the tape at least twice per day, removing any tape with the wiggling worms attached to it.
4). Your worm problem will be greatly reduced (if not gone) by the third day!