Odonata of Bangladesh

The taxonomic Order Odonata is divided into three subclasses: Anisoptera, which encompasses dragonflies; Zygoptera, which includes damselflies; and Anisozygoptera, which contains intermediary species between these two groups. The Anisozygoptera suborder has only two living species, and none of them are found in Bangladesh. The Latin word Anisoptera translates as 'different wings'. The dragonflies are called Anisoptera because of their dissimilar hindwings and forewings. The hind wings of dragonflies are larger than the forewings, and their shape is also different. On the other hand, Zygoptera means 'same wings' and is named so because of the similar shape and size of their forewings and hindwings. Although dragonflies and damselflies share many similar features, these two suborders can be distinguished easily by comparing key distinguishing features.

1. Dragonflies have big eyes that most often touch each other at the top of the head, while the eyes of damselflies are always separated and appear on each side of the head. (Figure 1)

Figure 1: A. Head of dragonfly — The eyes are attached at the top of the head.
B. Head of damselfly — The eyes are separated.

2. While perching, the wings of dragonflies remain open, whereas damselflies keep their wings closed during perching (except for the Lestidae family). (Figure 2)

3. The hind wings of dragonflies are larger than their forewings. Additionally, the base of the hind wings is broader than the base of the forewings. (Figure 2)

4. Dragonflies have a bulkier abdomen, while the abdomen of damselflies is long and slender. (Figure 2)

Figure 2: A. The dragonfly perches while keeping its wings open. The base of the hind wings is broader than the forewings, and the abdomen is bulkier.
B. The damselfly perches while keeping its wings closed. The abdomen is slender, and the bases of the forewings and hindwings are similar.