Daniel J. Hayes Jr., the Mayor of Cambridge, is up for re-election to the City Council next month. Facing a tough fight, the good Mayor three weeks ago launched a verbal fusillade at the nearest vulnerable and harmless target, the city's hippie population. It may prove successful politics, but now he is threatening to turn his useless diatribe against long hair into a more perilous experiment in illegal harassment.

In recent days, the Mayor has plugged for a series of midnight raids and wholesale arrests. He has on occasion called in television cameras and even free-lance photographers to document the "filthy situation" that he has found hippies living in. City health and fire inspectors have suddenly become meticulous about ticketing violators--in apartment houses where hippies live. As the Mayor himself admits, "I've warned the landlords that if they do rent to hippies, they'll be in for all sorts of problems."

Such blunderbuss terror tactics have little to do with firm and wise law enforcement. Nor does the city's announced intention of blackmailing hippies with a scattergun enforcement of vagrancy laws: arrested hippies must either go to jail or get out of town.

A crackdown on drug use by hippies--if it is necessary, and if that is what the Mayor is really concerned about--would be better served by a lot less bluster and a good more sober investigation of the extent of the problem.

Random and abusive use of police authority threaten the city's well-being and its citizens' respect for law far more seriously than the minor irritations occasioned by transient hippies.