A British tourist and his wife were left stunned when they came across this strange sight on a hike in northern Spain: a "snake" that was actually hundreds of caterpillars marching in line. <br /><br />Video shows what appears from a distance to be a long snake on a dusty track, filmed along the Camino trail between San Sebastian and the village of Pasaia.<br /><br />But the reality might be even scarier: these fluffy caterpillars line up head-to-rump in single file can fire out their barbed hairs, causing stinging in the eyes of anyone that aggravates them.<br /><br />Writes filmer Will Oliphant: "I'm fairly scared of snakes, so I approached with caution, but when I got there I was surprised to see that it was actually hundreds of little caterpillars. <br /><br />"We had a look around and there were a couple of other smaller chains of caterpillars walking in a similar fashion. <br /><br />"Luckily we didn't go too near them as it turns out that they are a fairly dangerous breed called the pine processionary caterpillar (thaumetopoea pityocampa), which can actually fire out its barbed hairs, causing stinging and irritation to the eyes. <br /><br />"We had noticed lots of cotton-wool like structures in the surrounding pine trees during the walk, which it turns out are actually a form of a nest that these animals build."<br /><br />According to reports, the species are native to southern Europe.
