Hundreds of bee hives worth over a half million dollars shipped to California’s Central Valley for the annual almond tree pollination were stolen on January 17, the Los Angeles Times reports.

Montana beekeeper Lloyd Cunniff, owner of Beeline Honey Co., shipped 488 bee hives to Sutter County in mid-December to service his almond grower pollination contracts. But after tending his bees in a grove near Meridian on Monday, he returned Tuesday morning to find his $542,000 of hives missing.

Bee pollination is not only important to rural agricultural communities throughout the Central Valley; it also provides a global economic benefit of about $290 billion in 2015.

There are an estimated 115,000 – 125,000 beekeepers in the United States. Although the vast majority of beekeepers are hobbyists with fewer than 25 hives, there are a few thousand commercial operators with 300 or more beehives.

The 2.6 million domestic honey bee colonies in the U.S. produced 149 million pounds of honey in 2013. With a wholesale price of about $2.12 a pound, the crop was worth about $317 million. California was the fifth largest American producer with 10.9 million pounds, worth $22.9 million, according to the National Honey Board.

Because millions of acres of U.S. fruit, nut, vegetable, oilseed and legume seed crops worth about $19 billion depend on bees, commercial operators are paid by growers to migrate their colonies each year to provide pollination services. But with demand drastically outstripping California’s local supply, Beeline travels 900 miles from Choteau, Montana each year to service contracts around the Sacramento area.

According to government U.S. agricultural data, the cost of renting honey bee hives for almond pollination has vaulted for about $50 per hive in 2003, to $150-$200 per hive today. It now takes more than a million bee colonies to service California’s annual crop.

After 500 hives were stolen last year, the California State Beekeepers Assn. issued an advisory to beekeepers across the state to beware of an “unprecedented” rise in beehive thefts.