That "scum" is probably some 17 year old kid who's a day camp counsellor and probably doesn't know the first thing about unions or solidarity. I think this is a case where education is called for, stat.  When a large portion of your membership are part-time, seasonal kids, you've got to do some major education on the basics.

Like telling them that, in fact, they probably CAN find part-time minimum wage jobs for the rest of the summer (which is what they should be doing instead of undermining their union), but that the reason their jobs pay more than that is because their union FIGHTS for those wages.