How monsoon in Delhi affected the number of dragonflies and damselflies

The number of species has halved, from 16 last year to eight this year at Kalindi Biodiversity Park, near Okhla. The number of individuals has also fallen from 3,348 last year to 2,563 this year. “There are a few indications. If you look at the biodiversity parks on the floodplains – the Yamuna and Kalindi biodiversity parks – the high flood earlier this year meant we lost some of the marshes, which affected the breeding of dragonflies and damselflies,” Khudsar said.

“In the biodiversity parks in the Aravalli ecosystem, with a few water bodies, there was rain early in the monsoon, but the dry spells meant that some water dried up,” he further said.

Delhi recorded excess rain in June and July, followed by a deficit in August and September.

At the Neela Hauz Biodiversity Park in Vasant Kunj, 256 dragonflies were counted this year, down from 323 last year. Similarly, at the Aravalli Biodiversity Park in Vasant Vihar, the count is down from 555 last year to 344 this year.

Different habitat requirements for different species means that the count of some species has increased, while that of others has decreased, Khudsar explained. At the Yamuna Biodiversity Park, near Wazirabad, more individuals were counted this year –647 compared to 357 last year – but the number of species was 21, down from 23 last year.

While the number of species indicates diversity, the number of individuals points to the density of the creatures in the area. “In general, they need marshes and how much water is required for individual species plays an important role. A few years later, this data will help us know how climate and extreme weather affect these tiny creatures. They are important as they are biological control for mosquitoes – they feed on mosquito larvae,” he said.

These also indicate water quality and the health of aquatic ecosystems, since they lay their eggs in or near water that is required to be clean.

There has been an increase in the number of dragonflies at the Tughlaqabad biodiversity park. The area had only 81 individuals and seven species last year, but this year it increased to 445 individuals and 14 species. Khudsar attributed this to the cleaning up of the sewage in the area. Species that were most spotted this year include the Ditch Jewel, Scarlet Skimmer, and Wandering Glider.