Bud Light's Lime-A-Rita boom

The Bud Light Lime "Ritas" franchise is getting bigger.

Looking to capitalize on the success of Bud Light Lime-A-Rita, Straw-Ber-Rita and the seasonal Cran-Brrr-Rita, Anheuser-Busch is doubling down, adding two new permanent flavors to its lineup of margarita flavored malt beverages.

Joining Lime and Strawberry in the Ritas franchise are Mang-O-Rita and Raz-Ber-Rita, which hit shelves nationwide on Monday.

The Ritas franchise has been a bright spot in the Anheuser-Busch portfolio at a time when overall beer volumes are flat and consumers, especially millenials, are turning to the variety offered by craft beer, wine and spirits.

Anheuser-Bush says the Ritas franchise is helping to capture some of the consumers who are looking outside the beer category.

"40 percent of this volume has come from outside of beer," said Pat McGauley, vice president of innovation at Anheuser-Busch. "It has the Bud Light name on it so it attracts people who are interested in the Bud Light brand but it also attracts people who may not have been in our franchise before."

Bud Light Lime-A-Rita was launched in 2012 and became the second-best selling new product launch that year, behind Bud Light Platinum. Straw-Ber-Rita followed the next year and became the largest share gainer in the beer industry in 2013.

Lime-A-Rita and Straw-Ber-Rita are the number one and number two brands in the flavored malt beverage category, and combined are larger than the category's next seven brands, according to industry researcher IRI, which tracks off-premise sales.

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With the release of Mang-O-Rita and Raz-Ber-Rita, Anheuser-Busch is continuing to push sampling by rolling out a Mix-A-Rita 18-pack, which includes six Lime-A-Ritas, four Straw-Ber-Ritas, four Mang-O-Ritas and four Raz-Ber-Ritas.

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While the brand has seen success off-premise, consumers can expect to see a greater push to market the Ritas franchise on-premise in bars and restaurants this summer. McGauley sees on-premise as an untapped market.

"We know bars that aren't carrying margaritas are a great opportunity and an area where the Lime-A-Rita family may be the most successful," he said. "This year we'll significantly support on-premise promotional activities and expect getting people to try it for the first in on-premise will drive more people to buy off-premise."

Consumers should also not be surprised to see more seasonal flavors in the future.

"We look at it like a (McDonald's) shamrock shake type of thing. The Cran-ber-Rita seasonal drove a lot of excitement and interest in the market place and we ran into some out of stock situations," said McGauley. "Cranberries are very relevant at that time of the season, so the adding a seasonal element to refresh the line at that specific time of year really paid off for us."

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As for who is drinking the Ritas, Anheuser-Busch says the demographic is more evenly split than might be assumed.

"It's almost a fifty-fifty, male to female split," said McGauley. "I think a lot of people think it's mostly females drinking them and while it does skew slightly more female, there are a lot of males drinking the Ritas."

—By CNBC's Tom Rotunno. Follow him on Twitter @TomRotunno.