"Bobae, go!" The trainer snaps her fingers and the English springer spaniel dashes off to sniff the lofty wooden pillars at Gyeongbokgung palace, one of South Korea's most important cultural heritage sites. Suddenly Bobae stops sniffing and sits and stares at a spot on one of the pillars. She has found what she was searching for -- two tiny termites. Back in England's West Midlands, Bobae and her canine companions, Woori and Boram, were trained to sniff out drugs or explosives. Now they search out destructive termites threatening South Korea's historic palaces and temples, which are built mainly of wood. "It's much more efficient (than other methods) and their detection is very accurate," said Jang Young-Ki, a specialist at the Cultural Heritage Administration. "The dogs' job is to scan and filter the area to narrow down places which researchers at the administration should be looking for." Using two of the spaniels and their trainers, it takes only two to three hours to sweep the whole of Gyeongbokgung. The search for termites could otherwise take many more hours, or even days. Gyeongbokgung, the grandest of Seoul's five main historic places, has 13 main buildings spread over 34 hectares (84 acres) in the heart of the city. The dogs are trained not to scratch or bite the wood when they detect termites, to avoid damaging it. Instead, they sit rigid to indicate the spot. The dogs are supplied by the Samsung Detector Dog Centre, which bought them from a police dog training school in the West Midlands. In a training process similar to that used for explosives or drug detection, trainers let the spaniels smell termites, hide the insects and let the dogs practise searching until they get it right. The Cultural Heritage Administration sets annual work schedules for the dogs after its researchers assess the possibility of termites in various buildings. The aim is to stop the bugs chewing up the woodwork from the inside before it's too late. "If termites can be seen with the human eye, it means there's nothing left inside the pillars. Dogs are able to smell the termites, so that we can work on it before it's too late," said Jang. Bobae, Woori and Boram started their Korean assignment in 2007 and typically take 10-12 trips a year all over the country. While two are on the road, the third takes a rest. They are not only hard-working but easy to motivate. When the dogs make a find, trainers bounce a tennis ball for them to catch. "To us it's work, but to them it's like a game. If they find termites, they get the ball. It's simple and they love it," said Ha Woo-Jong, manager at the detector dog centre. Apart from the termite dogs, the centre trains and donates 10 to 12 guide dogs for the blind every year. The three spaniels have worked well until now, but eight-year-old Woori and the other two, both aged seven, will have to retire eventually. South Korea could also use more sniffers to guard its imposing wooden cultural treasures, some of them original and some faithful reconstructions. "It would be much better if we had more dogs helping detection. They are definitely helpful and there are just too few of them to cover so many sites," said Jang. And because Korea's climate is becoming warmer and more humid, the number of termites may well rise. "Detector dogs retire at age 10 to 12," said Ha. "Since it takes at least one and a half years to train them from scratch, it's time to start looking for the second generation."