Hairy crabs are one of the most sought-after delicacies during the Mid-Autumn Festival season. The festival itself falls on the 15th day of the eighth lunar month, usually sometime between September and October in the Gregorian calendar. It is also the best time to eat crabs because the two months fall at the height of the crab-fishing season.

However, this year the festival will arrive earlier, on Sept 8, before the crab fishing season kicks off. Still, all the big online grocers have cashed in on the golden festival time by issuing eye-catching vouchers for crab at end of August.

Ben Lai Sheng Huo (benlai.com), which literally translates as "Original Life" will sell 12 types of vouchers for Yangcheng Lake hairy crabs ranging from 398 yuan ($65) to 3,698 yuan. The vouchers are valid from Sept 26 until Dec 31.

Many online retailers of fresh produce and seafood are currently sourcing the origins of their fresh items to ensure quality and freshness.

According to Ben Lai Sheng Huo 's promotional pamphlet: "Our professional buying team made 15 study tours to Yangcheng Lake in 2013, and finally decided to cooperate with Yu Sannan, which has 20 years' experience of farming crabs, and is dubbed 'Number One' among the crab breeders in its locality. Yu Sannan's crabs went on sales last year on our website, winning great praise from consumers. This year, we will continue to sell Yu's crabs." The pamphlet also featured photos of Yu, and of the crab-farming operation.

Lelife.com, an e-commerce site that is a subsidiary of Leshi Television, a online video portal, began online operations on Aug 18, with the aim of marrying the Internet and eco-agriculture, and cooperates with 3,500 farms and seafood producers nationwide.

The first products it launched were hairy crabs from six major production areas, including Gaoyou Lake and Yangcheng Lake in Jiangsu province, and Panjin in Liaoning province.