From a human point of view, odonates are harmless insects; that is, they do not have any direct or indirect detrimental effect whatsoever on human beings. However, from an ecological point of view, they are a highly significant group of organisms. Since odonates have well-known habitat requirements (fresh water ecosystems that vary from coastlines to tropical rain forests) and are easily identifiable, they are one of the best indicators of ecosystem quality and biodiversity. Scientists have even developed The Dragonfly Biotic Index – comprising data on geographical distribution, conservation status and ecological sensitivity – to monitor biological water quality of an ecosystem, which makes this task far more effective and simple. Population studies on odonates are widely used to monitor landscape changes also.
The capacity of odonates in controlling harmful insects such as mosquitoes, blackflies and other blood-sucking insects (both adults and their larvae) make them important bio-control agents. Many countries have successfully employed odonates to control mosquito population especially in urban areas. Needless to say, they are best friends of farmers, as they play a crucial role in controlling insect pests.
Studies have shown that globally about one in every ten species of odonates are threatened by extinction. The single most reason for this decline is the destruction of aquatic habitats. Other factors such as wetland reclamation, land filling, canalization of streams and rivers, deforestation, introduction of invasive species etc, are also posing major threat to the very existence of these magnificent insects.