The Erziping Trail (二子坪步道) is a forest track located between Mount Miantian (面天山) and Mount Datun stretching 1.7 kilometers. Along the trail is typical subtropical broadleaf vegetation, with myriad plant types thickly intermingled. The trail is busy with butterflies and their nectar-plant food sources, and for good reason: this trail has long been known for great butterfly viewing, and long ago came to be called the Butterfly Corridor. Naturalists have recorded 130 separate butterfly species from 5 families in the area, 80% of the total of the 180 found on Yangmingshan.

Mid-May through September is the prime butterfly season on Yangmingshan, with beautiful Lepidoptera bursting onto the scene. It's not unusual to see dozens of different species in a single day. Chestnut Tiger butterflies (青斑蝶) visit in terrific number around the time of the Dragon Boat Festival (端午節), so be sure to walk along the Butterfly Corridor during this period, when the impressive spectacle of thousands of dancing butterflies is a daily occurrence.

As part of this year's butterfly season, the Yangmingshan National Park Administration is staging a special program called "Images of the Grass Mountain Universe" (草山影像寰宇) from May 19 through July 31. A number of films will be screened, including Butterflies Dancing Over Grass Mountain (蝶舞草山), introducing Yangmingshan's butterflies, Lullaby of the Forest－The Leaf-rolling Weevils (森林搖籃曲), and Encounter with the Insects of Yangmingshan National Park (蟲相逢). These will be a thrill for all those intrigued by the wonder of nature, and all are welcome.

Beyond the beauty of the butterflies, in this broadleaf forest situated 800 meters above sea level can be found red nanmu, black pine, Formosan sweet gum, and large-leaved nanmu in significant numbers. You'll also come across scattered samples of Formosan turpinia, common eurya, dark spotted cherry, and bird-lime tree. Add to this the endless panoply of shrubs, ferns, mosses, and other plant life and you have a brilliantly textured forest kaleidoscope. The forest is home to a wide variety of insects, birds, and reptiles, and as you move along ever deeper into this calming environment, regaled by the singing of the cicadas, the heat of the summer fades away.

The trail is paved with crushed stone, and is shaded and cool along its length. It's about an hour of gentle walking to the Erziping Recreation Area (二子坪遊憩區), situated in a volcanic depression between the main Mount Datun peak and Mount Erzi (二子山). There are a couple of man-made eco-ponds here, stocked with more than 50 water-plant species. The waters here run slow and clear, and from spring to early autumn the damselfly is commonly spotted. Females like to lay their eggs on waterside stones or water-surface plants, and in summer you can spot large groups of the Euphaea formosa, a Taiwan endemic damselfly, foraging for food or perched at rest. The Euphaea formosa lives in habitats up to 1,500 meters that have running streams, and is Taiwan's most widely distributed damselfly, with the highest population. Its active, enchanting bearing draws curious adults and kids to the waterside.

If you're still thirsting for more, head down the trails to Qingtian Temple (清天宮) in Beitou (北投), or follow the signposted paths to Datun Nature Park (大屯自然公園). This park is centered on a small, natural mountain lake. Eco-restoration work has been undertaken to restore the vegetation to its natural state, and the park is bordered by thick temperate broadleaf forest. Watch the resident fish lolling about from the lovely wooden bridge spanning the water, gaze over the misty mountain landscape, listen to the frogs croaking in chorus, and experience the joys of nature in summer.