On lake Erie, you'll see more of the the "prickly pear" style of flea....... they're spiny water fleas and no where near as troublesome on fishing lines.
On Ontario, we see more of the difficult to deal with type...... fishhook water fleas. But, once the fishhook numbers start to go down, you'll see some of the spinys on Ontario too
I'm guessing that the fishhook variety is more cold water tolerant, and a way bigger pita.