Justin Noel, owner of Greenwich Village cocktail bar Sweetwater Social, was packing up supplies from a liquor industry event the other day, when he caught sight of an unattended box filled with valuables. He promptly looked both ways, snatched the box and headed directly for the door.

Its contents weren’t gold, though for some in the restaurant business right now, they might as well be. No — these were limes.

“Like our forefathers, the European conquerors, I just lay claim to them,” says Noel. “Every little bit helps.”

It’s not the first time in recent weeks Noel lime-looted an event: In the past, he’s grabbed five-gallon bar buckets, filled them with citrus and walked back to his restaurant.

Welcome to the great lime panic of 2014.

A huge shortage is the result of a nasty cocktail of conditions in Mexico, where 97 percent of US limes are grown. Heavy rains knocked the blossoms off many trees, reducing yield. A bacteria that’s long been ravaging citrus trees in Mexico didn’t help either, but the real trouble came when criminals and drug cartels started looting the groves and hijacking delivery trucks.

A case of limes used to cost as little as $30; prices have shot up to as high as $200. And the limes are smaller — golf-ball-size fruit that doesn’t produce much juice.

“All of a sudden, this thing I can always have is a product of scarcity,” says Phil Ward, owner and beverage manager of Mexican joint Mayahuel in the East Village. “I don’t think I’ve seen anything like this.”

Even the casual restaurant-goer may have noticed lemons replacing limes on taco plates, lime-based drinks disappearing from menus and lemons making an understudy appearance as cocktail garnishes. Ordering a Corona? Many bartenders won’t give you a lime unless you demand it.

And so, with the brutal winter finally breaking, the limepocalypse has set off a full-scale panic for bartenders and restaurant owners, with a lime black market of sorts popping up around the city. Some are adding a dollar or two to the cost of a margarita; other spots are taking the hike on the chin, hoping prices drop soon.

“People are basically claiming to be citrus drug dealers,” says Noel, only half-joking: Bartenders report friends from around the country are posting pictures on Facebook of limes wrapped and labeled in plastic bags like pounds of cocaine.

One savvy New Yorker, an air conditioner repairman with friends in the restaurant business, has been driving a rented U-Haul truck to an orchard in Florida and filling it with limes to sell to bars and restaurants in Washington Heights.

“He saw an opportunity to profit from this,” says Esteban Ordóñez, owner of tequila-centric bar Burning Waters Cantina in Greenwich Village, who knows the enterprising lime trucker. “He’s working to prepare A/C units, and he’s getting ready for the summer, and he put one and one together.”

The hauler expanded his operation to two trucks last week, though Ordóñez and other bar workers say that it’s a short-term solution. (The smuggler declined to comment to The Post.)

Ordóñez went on a hunt of his own, driving around Queens and Brooklyn looking for small produce shops that might have a stash. He found one, Patel Brothers in Jackson Heights. The price was $110 for a case of about 200 limes — still costly, but $50 cheaper than his distributor.

“Next time we came back, they were out — no limes,” says Ordóñez, who then haggled the owner of a nearby stand down to $135 per case. Still, he was only allowed to buy three.

“Everyone is joking about the size of the limes we have now. They look like little pingpong balls,” Ordóñez says. “A lot of people have commented, ‘Is that a real lime?’ ”

You won’t find much relief in the city’s grocery stores, either: The Gristedes at Eighth Avenue and 54th Street is selling limes for a whopping $1.50 each. Whole Foods raised prices from 50 cents to 79 cents, but according to regional spokesman Michael Sinatra, the company doesn’t want to pass on any more hikes to customers. Meanwhile, C-Town on Graham Avenue in Williamsburg used to sell three limes for $1; now three cost $2.29. That’s still better than two weeks ago, when the store had no limes at all for about three days, according to manager Alex Cortez.

Some bartenders are treating the shortage as a way to flex their creativity, experimenting with different acidic ingredients, such as grapefruit.

Ricky Camacho, executive chef at Hell’s Kitchen’s Añejo, launched a lemon margarita, which he calls “just as amazing and refreshing.”

Other places aren’t as versatile, such as Steve’s Authentic Key Lime Pies in Red Hook, which only makes lime-based products.

“Our [cost] basically doubled overnight,” says owner Steve Tarpin.

When crops are good, the shop freezes extra juice for an emergency (a hurricane affecting the Mexican crop is what’s usually expected; drug cartel-orchestrated gouging is not). But while Tarpin is hoping prices will drop before his emergency stash runs out, the experience has inspired him to take matters into his own hands: He’s researching building a rooftop greenhouse to produce his own supply.

“We’re going to see if we can get something going here,” says Tarpin, who is headed to the University of Florida next month to consult some horticulture experts. “It’s best at this point that we look into a viable alternative.”

He’s likely not the only one taking a DIY approach. Try to find certain kinds of lime trees at Four Winds Growers, one of the Internet’s largest sellers of citrus plants, and you’re out of luck.

“We are starting to run out of some varieties,” says Kerry Beane, e-commerce director for the Northern California-based grower.

And nurseries in New York City are bracing for a potential rush in coming weeks when lime trees arrive, says David Protell, owner of Chelsea Garden Center.

The panic is even causing some savvy drink slingers to treat their limes like bad cocaine — by cutting them with another substance. Mimi Burnham, bar manager at Blue Bar at India House in the Financial District, has concocted a mix — 70 percent lime juice and 30 percent lemon — to use in cosmopolitans and margaritas.

“I refuse to use Rose’s lime juice,” she says of the popular store-bought brand. “High fructose corn syrup is the first ingredient.”

Customers, however, aren’t so sweet on the idea of the sour lemon.

When asked if she’d try a lemon margarita, Bernadette, a 27-year-old from Jersey City, grimaced while drinking at Burning Waters on Thursday.

“I think I would throw the lemon wedge at them. What’s the matter with you? It’s not the same,” says Bernadette, who declined to give her last name because she didn’t want her United Nations colleagues privy to her drinking habits.

Her friend Dan, an accountant from Flushing, agrees.

“Alcoholic or nonalcoholic, I prefer a lime to a lemon,” he says. “It’s got a nicer flavor, not as bitter.”

At Sweetwater Social, some customers have even started asking if they can bring in fruit from their own personal stash so they don’t miss out on their favorite drinks.

And that’s fine by Noel. “Hell, I’m not going to have any issues with making a drink with your own limes.”