Best way to remove Ployclad Flatworms?

Happened upon a huge 4-5 inch flatworm while moving rocks last night. From what I have read if there is one that big that means there are tons of others.

Any tips on the best way? I have read about setting a trap with a snail or live clam. Hints on the most effective trap and bait would be helpful. Could I use the canned clam meat from the store?

Its too bad these are bad guys because it was a cool looking critter. But that explains where my snails have all gone, I was blaming my wrasse and hermits.  Not sure how long Ive had them but I have lost a whole  $60 order of Reefcleaners snails and probably 15 Giant turbo snails.