Studies of dragonflies in Hong Kong started in the 1850s. Black-banded Gossamerwing (Euphaea decorata) was the first dragonfly recorded here by Baron de Selys Longchamps in 1854. New species were continuously added to the local records by the concerted efforts of various researchers. To date, more than 130 species of dragonfly, including two endemic species and more than 10 species new to science, have been recorded in Hong Kong. They are from seven families of suborder Anisoptera (dragonflies) and nine families of suborder Zygoptera (damselflies).
All members of the order Odonata are known as dragonflies. The Odonata order is divided into three suborders including Anisoptera (containing mainly robust dragonflies), Zygoptera (known as damselflies) and Anisozygoptera. The majority of damselflies are much smaller and more delicately built than the Anisopteran dragonflies. However there are exceptions such as Ochre Titan (Philoganga vetusta), which is a huge and robustly built damselfly of similar dimensions to a medium sized aeshnid dragonfly. Structurally, damselflies are characterised by widely separated eyes, and wings narrow at base with hindwingss of similar shape to forewings and usually held closed together at rest. On the other hand, most Anisoptera in Hong Kong have eyes which are not separated, and the wings are usually held horizontally or depressed when at rest and the hind wing is always broader than the forewing near the base.
The habitats of our local dragonfly species are very diverse, including sandy and rocky streams, freshwater ponds, seasonal marshes, reservoirs, freshwater and brackish water marshes and waterfalls. Some species are more commonly seen than the others, such as Hong Kong Clubtail (Leptogomphus hongkongensis) is commonly found in muddy gravel areas with coarse sand in small wooded streams and trickles; while some species are rarer and more restricted, such as Hong Kong Tusktail (Fukienogomphus choifongae), which has only been recorded at one location in the New Territories.
