There’s a new trend in the craft segment; let me pour you a glass of it. If you can’t tell by the orange color or the homey aroma of pie wafting out of the mug, it’s pumpkin beer. It smells like pumpkin pie or the pumpkin muffins you see in bakeries this time of year. Don’t get hooked on it, though; just like the pie and the muffins, pumpkin beer will be gone by December. Get it while you can, or wait for next fall.

“Pumpkin beer” may seem bizarre to the uninitiated. Why would you want to stuff a squash into an innocent beer? I happen to know the first guy who did it in modern times, so I asked him.

In 1986, Bill Owens, who is currently wrapped up in the birth of microdistilling as president of the American Distilling Institute, was involved in the dawn of microbrewing, running one of the country’s first brewpubs, Buffalo Bill’s, in Hayward, California. Owens, along with being a brewer and a photographer, was then an enthusiastic gardener. He had a 70-pound pumpkin growing in his backyard and didn’t know what to do with it. “I had read that George Washington made beer and used pumpkins in the process,” he said. “So I decided to do the same.”

Owens cut up the pumpkin, baked it, then mashed it right in the malt with a batch of beer. The effect was disappointing: “The gourd family has a neutral flavor,” as he put it. Inspiration struck. He got a jar of pumpkin-pie spices at the supermarket—nutmeg, clove, ginger, cinnamon, allspice—made a tea with them, and put it in the finished beer. “Instant pumpkin ale!” Owens said.

Instant pumpkin-pie ale might be more accurate, although it begs an explanation of the missing crust. Still, Owens had learned the secret to cooking with pumpkin: It’s what you add to it that creates the flavor.

Owens sold the beer in his brewpub and made an annual tradition of it. Pumpkin beers were a novelty for years, merely a fun ale for brewpubs to offer each fall. Owens contracted with a microbrewer to bottle some for him, but no one thought this would ever rise above gimmick status.

The first inkling I got that something more was going on was five or six years back when I was talking to a brewer at a now-defunct Philadelphia brewpub. It was summer, and he mentioned that he only had a month or two until the “pumpkin zombies” showed up: “They show up in August asking, ‘Is the pumpkin beer out yet?’ ”

Dan Weirback makes one of my favorite pumpkin beers, Imperial Pumpkin Ale, at his Weyerbacher brewery in Easton, Pennsylvania. Around 2001, his wholesalers started asking him for a pumpkin beer for their customers, but he didn’t want to get involved in another fast-fading fad. After four years of hearing the same requests, he figured he had to listen.

“I decided if we were going to make one, we were going to make a big one,” he said. For each batch of Imperial, he blends 30 big, restaurant-size cans of pumpkin puree with enough malt for a full-bore 8 percent strong ale. All that pumpkin makes a beer that’s bright orange, and the spice leaps out at you.

I’m not the only one who likes it. Weirback says the beer has sold out in the first year he offered it, in 2005. He tripled production to 1,680 cases in 2006 and sold out again. This year, he had double that amount in pre-orders from his wholesalers and despite having made about 30 percent more, he says, “We’ll be out of it before the end of October.”

If you need more evidence, just glance at some numbers: BeerAdvocate, a beer-enthusiast website, lists 157 pumpkin beers. Or you can rely on a sure indicator of beer “hotness,” the presence of big brewers in a niche.

Anheuser-Busch introduced Jack’s Pumpkin Spice Ale in 2005 and has brought it out each autumn since. Coors brews Harvest Moon Pumpkin Ale as part of its Blue Moon line. It’s been doing so since 1996, despite Blue Moon’s initial low sales. Now that pumpkin beer has caught on, the company’s looking pretty smart.

But pumpkin’s a mess for brewers; even canned pumpkin puts a lot of fiber and color in the system. The spices can ruin a brewery’s plastic beer lines used in the beermaking process, flavoring every beer that comes after them. No one wants to disappoint the pumpkin zombies, though, and it does make a nice treat in the season and something fun for Halloween. (View slideshow.)

I’ve come to look forward to a pint of pumpkin beer each autumn. I don’t sit at the bar and have three slices of pie in a glass; that’s too much. But if the leaves fall and I don’t get my glass of pumpkin beer, something’s just not right.