All visitors to New York know you have to be careful of certain sorts in Central Park. It's a nice place, but look out for the muggers, purse-snatchers and bike thieves, to name a few. Now there is a new type preying on the public: the nibbler.

They caught one the other day. Steve Brill is his name. He was taken without a struggle, handcuffed and booked. Later he told his whole shameful story to a reporter: "We picked dandelions and a few other common weeds. We ate a few high-bush berries . . . a little bit of water mint . . . and some day- lily shoots."

In time the two undercover officers will no doubt testify that they observed the perpetrator as he perpetrated in the company of an ecology group that he was leading on one of his paid tours of the park. The two called fr backup help from fellow officers of the Parks and Recreation Department, and Mr. Brill, who has been regularly doing this sort of grazing and has been warned against it, was hustled off.

The tabloids fell asleep at the switch and did not cover their front pages with: "NAB HERBIVORE HORROR -- HE GLOATS: 'I ATE THEM AND I'M GLAD.'enry Stern, said, "Parks are to look at. Our motto is 'Please don't eat the daisies.' course. That's the unassailable point made by the authorities when they arrest people for picking blackberries along the highway or eating somebody else's day-lily shoots: "What if everybody did that?" On the other hand, given the nature of the activities of some who frequent Central Park, it might be better if they, at least, were doing that rather than what they're doing now, especially if it got two undercover officers assigned to each of them.