Dread Scorpions can be found at Rumrunners Isle, Padres Del Fuego/ElSudoron/Padres beach, outcast isle, and likely a few other places that escape me at present.
Here is a link to a handy chart many use to various find POTCO enemies:
http://www.piratesonlineforums.com/f...ead.php?t=4281
You can also click my sig for my POTCO Enemy database you can use to find things.