This week's heat wave has sent a whole lotta folks heading for Margaritaville.

Or Gimlet-ville. Or Gin-and-Tonic-ville. Or any ville that swizzles a bracing bit of lime with booze and enough ice to beat the high temps.

For many, that hit comes from Rose's Lime Juice, a sweetened citrus cordial first used to stave off scurvy among sailors who needed vitamin C but now one of barkeepers' main go-to sources for lime flavoring.

But Rose's is proving tough to find — here and across the country.

Karen Himle of Minnetonka looked in vain from the Twin Cities to Brainerd. The owner of a liquor store in Nisswa told her that "the local restaurants bought up every last drop."

Persistence (desperation?) finally was rewarded last weekend when she found some Rose's in Crosslake.

Aaron Sorenson, communications manager for Lunds and Byerly's, said that supply is "a bit sporadic at this point" due to an issue with the manufacturer. What that issue is, he doesn't know. But for now, stores' supplies are changing "on a week-to-week basis."

What's going on? There are several theories but no definitive answer.

In a bartenders' thread on the online chat site Reddit, one supplier said he'd heard that a lime farm in Mexico used a pesticide not allowed by the U.S. government. He'd said he'd gotten the info from someone with Mott's juices, which is owned by the Dr Pepper Snapple Group, which also owns Rose's.

The company did not respond to a request for comment.

Another reason comes from Mexico News Daily, which reported in April that lime prices soared by 41 percent when late cold weather and early rains hurt the crop. Not helping matters: A citrus disease called the huanglongbing plague is gaining a foothold; no remedy has been found.

Another factor: We love limes. In the 1970s Americans consumed less than half a pound per person per year. Today, we're up to 2½ pounds.

With Florida's groves wiped out by disease and hurricanes in the early 2000s, Mexico is the world's largest producer and exporter of limes, providing 95 percent of the U.S. supply.

There are recipes for making your own lime cordial. Here's one:

Raw Lime Cordial

Makes about 2 1/2 cups.

Note: This recipe appeared in the New York Times on May 2, 2011.

18 limes, room temperature, very ripe, well puffed and heavy

• 2 1/2 c. sugar

Directions

Wash limes in warm water, scrubbing with your hands or a vegetable brush, and let them dry on a dish towel. Peel them with a vegetable peeler, removing as little of the underlying white pith as possible.

Cut limes in half and juice them. This should produce about 2 1/2 cups of juice.

In a glass or plastic coverable container, add sugar to juice and stir until fully dissolved, 3 to 5 minutes. Crush peels in handfuls to release the oils as you add them into the juice mix. Stir well.

Cover and refrigerate for 12 to 24 hours. When ready, strain the cordial in a fine mesh strainer. Discard peels. Funnel cordial into covered container or capped bottle and return to refrigerator for another day to cure before using.