It’s the busiest time of year for beekeepers. Billions of honeybees from across the country have been shipped to California for almond pollination season.

Almonds are California’s top crop, bringing in billions of dollars for the state every year. The state grows so many almonds, in fact, that they rely on out-of-state beekeepers to ship in pollinators to allow the trees to bloom.

But thieves have stolen more than a thousand beehives in the past few weeks, and it’s costing beekeepers. It’s been a growing problem that has prompted some to start putting GPS trackers inside the hives.

BeeHero, a company that has developed a sensor to help beekeepers maintain their hives, says the location tracking feature has actually helped get stolen equipment back.