Now, a new breed of crate rustler is cashing in by swiping thousands of the containers from loading docks and selling them to shady recyclers.

The containers are chopped into bits and shipped to booming factories in China to be made into a variety of products, from pipes to flower pots.

Facing an estimated $80 million in annual losses from the thefts, dairies across the country are moving to stop the plastic pilfering. In California, companies are even hiring private detectives and staging sting operations.

"We saw them disappearing into this black hole," said Rachel Kaldor, executive director of the Dairy Institute, a trade group in Sacramento. "We just don't know who's stealing these crates off the loading docks."

In the past two years, the high-density polyethylene has joined a growing list of materials that are being stolen and sold via a thriving underground recycling network.

Among other things, thieves target copper, aluminum bleachers, beer kegs, even cemetery vases and nameplates.

It took a while for dairies to determine what was happening to their crates.

"If it were just college kids taking them, the dormitories would be overflowing with milk cases," said Stephen Schaffer, general manager of Alta Dena Dairy near Los Angeles.

Source: Forbes