Earl Wilson/The New York Times

The high price of oil is not the only effect of commodity inflation hitting the streets of New York. A surge in the value of copper, iron and other metals has fueled a wave of thefts from sidewalks, roadways and rail yards in the last few months.

On Wednesday alone, the New York police arrested three men for stealing hunks of cast iron — grates made to protect tree roots and manhole covers weighing as much as 300 pounds. The arrests followed reports of the disappearance of dozens of the grates and covers across the city and came on top of a continuing spree of thefts of copper wire from utility cables.

“It’s about money,” said Kevin Rafferty, president of Dublin Scrap Metal in Newark. “The economy’s tough, and people are looking to sell whatever they can find to sell.”

Mr. Rafferty, who said his company would not buy manhole covers or pieces of train rail that people showed up with, said the run-up in the prices of metals could also be driving up thefts. Still, he said, stealing a manhole cover from a city street is a true sign of desperation. Iron is worth only about 15 cents a pound, compared with about $3 a pound for copper, he said.

That disparity helps to explain why utility companies like Consolidated Edison usually have to contend with thefts of copper-filled cables far more often than the pilfering of manhole covers. Last year, Con Ed counted 133 thefts of its cable and just 2 stolen manhole covers.

But that was before Andrew Modica came along, the police say. On Wednesday night, detectives in Brooklyn arrested Mr. Modica, 46, in connection with the thefts of dozens of Con Ed’s manhole covers in Brooklyn and Queens.

Inside a stolen Ford pickup truck with stolen Connecticut plates, the police said, they found a hydraulic jack and two J-shape metal hooks that Mr. Modica used to hoist the covers from roadbeds into the truck. He admitted that he had taken more than 15 of the missing covers and sold them for about $30 each to two scrap yards in the city, the police said. To avoid suspicion, Mr. Modica wore a reflective vest like the ones used by Con Ed repair crews, the police said.

The police declined to identify the buyers of the manhole covers.

Mr. Modica, it turns out, had firsthand knowledge of how to remove manhole covers because he had worked for a company that replaced them for Con Ed. That company, Safeway Construction Enterprises in Maspeth, Queens, employed him until late last year, said Shuta Waki, a manager with Safeway. Mr. Waki would not discuss the circumstances under which Mr. Modica left the company.

Consolidated Edison

Mr. Waki said removing manhole covers “was part of his job.” But Mr. Modica would have been working with one or two other men to lift the covers. He expressed doubt that Mr. Modica could have taken the covers by himself and was surprised to hear that the police said Mr. Modica had left open manholes that posed hazards to drivers and pedestrians.

Con Ed officials were also dubious that Mr. Modica had worked alone. “To a lot of people here, it was quite surprising that it was one person who was doing this,” said Michael Clendenin, a spokesman. He said the company believed Mr. Modica was responsible for the bulk of the missing covers, but “we’re certainly not going to assume that there aren’t other people out there who might try to do the same thing.”

Mr. Modica was charged with possession of stolen property, reckless endangerment, petit larceny and criminal impersonation, the police said.

He was the third man arrested on Wednesday for taking molded metal off the streets. Early that morning, a police officer in Midtown Manhattan stopped a van and found three grates that had protected trees on West 48th Street. The driver admitted that he had previously stolen at least a dozen similar grates from the sidewalks along 46th Street between Eighth and 10th Avenues, the police said.

A passenger in the van was wearing a reflective vest that belonged to the Metropolitan Transportation Authority, although he did not work for that agency, the police said.

Business owners along that stretch of 46th Street, known as Restaurant Row, were so distressed about the absence of the grates and fearful that pedestrians would trip over the unprotected tree pits that the Times Square Alliance had offered a $1,000 reward for help catching the thieves. Tim Tompkins, the president of the alliance, said that a witness had provided some information to the police about the thefts but that he did not yet know if the person would receive a reward.

The scrap metal industry has a system for spreading word of the theft of metal items, like the load of used rail spikes and rail plates that disappeared from a New Jersey Transit rail yard in Raritan, last month. But Mr. Rafferty said that even a vigilant metals buyer would have trouble spotting unmarked pieces, like the tree grates, buried in a truckload of junk.

Kevin Lawlor, a spokesman for the Institute of Scrap Recycling Industries, a trade organization in Washington, said, “We don’t like to put the onus on the scrap dealer to make decisions about what’s stolen or not stolen.” Still, Mr. Lawlor said, “The manhole covers is a unique situation because people should know that everyday citizens don’t walk around with a manhole cover.”