It turns out American consumers' expectations aren't aligned with those from other parts of the world. “We were doing research into Starbucks going into other countries and people who travel a lot,” Fitzgerald said, noting that Canadians aren't nearly as interested in pumpkins, despite their proximity to the U.S. “American customers expect to see pumpkin spice in other countries when they go abroad, but it all goes back to Thanksgiving. [Other countries] don’t have Thanksgiving, but we do.” From a marketing perspective, the American conception of autumn gets lost in translation.

Staying ahead of pumpkin-spice trends requires quite a bit of planning, and is a year-round endeavor. Developing the right packaging, coloring, and flavor can take six to eight months. It may not seem like consumers have an appetite for any more pumpkin-spice products, but Flavor and Fragrance Specialties still gets requests from companies eager to capitalize on the trend. "I think there's still growth," Fitzgerald said.

Whether there is room for growth or not, it's certainly the case that there's demand for pumpkin-spice products is really high. A black market for pumpkin-spice syrup has formed on eBay, where devotees sell jugs of the viscous flavoring for as much as $100. Hugh Merwin, an editor at New York Magazine's Grub Street blog, recently chronicled his adventures acquiring the highly prized syrup and then dousing all of his food in it for two days.

“Around March or April," Merwin told me, "I noticed there was a subculture of people who will alert people with Starbucks locations that still have pumpkin-spice lattes." When he began studying the subculture dedicated to the pumpkin-spice latte, he noticed listings for the flavored syrup on Craigslist and eBay.

Not long after August's unveiling of pumpkin-spice products, Merwin told me, jugs were popping up online—smugglers weren't waiting until the off-season to sell. The containers appeared authentic, and weren't limited to the Starbucks variety. Dunkin' Donuts is fast becoming a competitor in the quasi-illegal online pumpkin-spice space—its jugs tend to sell for only a smidgen less than Starbucks'.

The provenance of the goods sold on eBay, though, is unclear. One of Merwin's inquiries—sent to an eBay seller that went by "californiasuns"—was met with a rambling, whimsical response. "The game of acquisition & liquidation is strung together with many parts and avenues," the user wrote, before going on to say, "We are law abiding, and as such we do not partake in unlawful acts."

Once Merwin secured a container of Starbucks' syrup, he compared the ingredients to the ones in the Fontana product sold, legitimately, online. The biggest difference he found is that Fontana's product contains corn syrup and potassium sorbate (a preservative), both of which are absent in Starbucks' in-store product. Otherwise, the two syrups looked similar.

“I don’t know if it’s the only difference,” Merwin said, noting that both products also have the vague terms of “natural and artificial flavorings,” which could encompass a variety of ingredients. “I haven’t tasted the two side by side.” (Online, verdicts vary on whether the taste is the same or not.)

One reason pumpkin-spice products sell so well is that people respond frenetically to anything that's labelled "limited time." Gingerbread-flavored drinks, Peeps, and McDonald's Shamrock Shakes all owe some of their success to this pattern. Despite this, the people behind the pumpkin-spice latte supply want to make it little less time-limited: “We’re pushing the season forward—this year, we started on August 20,” Fitzgerald noted. “But I don’t think we’ll go into July. That’s summer.”

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