Prelims Level
Mains Level
Prelims Syllabus : Environment- Biodiversity Mains Syllabus : GS-III- Conservation, environmental pollution and degradation, environmental impact assessment


  • A survey of dragonflies and damselflies held in the Silent Valley National Park (SVNP) has discovered eight new species, but reported an alarming decrease in the odonate population, raising concerns over the ecological impact of the successive floods in the State.

New Species:

  • The new species found in the survey includes the Hemicordulia asiatica (Asian Emerald), which was reported from the Periyar Tiger Reserve in 2017.
  • This rare dragonfly had gone unreported for over 80 years, and this was its second sighting from any protected forest in the State.
  • Macrogomphus wynadiccus (Wayanad Bowtail ), Onychogomphus nilgiriensis (Nilgiri Clawtail), Epithemis mariae (Rubytailed Hawklet), Palpopleura sexmaculata (Blue-Tailed Yellow Skimmer) and Neurothemis intermedia (Paddy Field Parasol) were the other interesting finds among dragonflies.
  • Agrocnemis splendidissima (Splendid Dartlet), Lestes dorothea (Scalloped Spreadwing), Onychargia atrocyana (Black Marsh Dart), Phylloneura westermani (Myristica Bambootail), Euphea disper (Nilgiri Torrent Dart) and Protostica gravely (Pied Reedtail) were some of the decorated findings among damselflies.

Findings of Survey:

  • Climate change has hit the Silent Valley National Park leading to a sharp fall in the population of dragonflies such as ‘global wanderer.’
  • Experts opined that this could be due to the aberrant rain pattern and successive floods that affected the state as the predaceous insects spend most of their lifetime as eggs and larvae under water.
  • Though there was an increase in different species found in the region, a decrease in the number is evident in each of them.
  • One disturbing finding is the fall in the abundance of dragonflies – a meagre average two sightings compared to 60 last year.
  • The insects spend most of their lifespan in water bodies.
  • The larvae could have been destroyed in floods which affected the region in the last two years.
  • Eight new species were discovered from the park. These include hemicordulia asiatica, which was previously reported from Periyar Tiger Reserve in 2017.

About Survey:

  • The second edition of the Odonate (dragonflies, damselflies) survey was held jointly by the volunteers of the Society for Odonate Studies and the Silent Valley Park.

Biological Indicator:

  • Odonates were great biological indicators and studies on them would provide crucial information on the health of aquatic habitats and variations occurring in the climate.
  • Odonates are good pest controllers.

Freshwater Indicator:

  • When a water system becomes degraded through human impact like pollution or damming, there is a change in the species profile away from sensitive specialists towards insensitive generalists.
  • A prominent group of species associated with water and that can tell us something about the state of our water resources is dragonflies – the collective term for true dragonflies and damselflies.
  • When they are young they live in the water as larvae, then later emerge as flying adults that grace fresh waters throughout the world, except the ice caps. Both life stages are predatory.
  • So these beautiful insects are near the top of the food chain and have few natural enemies other than birds. These are occasionally frogs, spiders and robber flies.
  • Dragonflies like the white malachite are excellent candidates for water assessment.
  • Using dragonflies it is possible to determine whether there should be concern about a system that is going downhill or whether a system is improving, and how well it’s doing.
  • Using dragonflies to this end is incredibly simple.

About Dragonflies:

  • Dragonflies are pushed away from their normal habitats when invasive alien trees like eucalyptus, wattles and pines shade the water and bank.
  • This means that the removal of alien trees from the banks of rivers, in particular, is an important nature conservation exercise.
  • Farm dams can encourage many species that would otherwise be very scarce in the area.

About Silent Valley National Park:

  • The national park is one of the last undisturbed tracts of South Western Ghats mountain rain forests and tropical moist evergreen forest in India.
  • It is located in the Nilgiri hills, Kerala.
  • This national park has some rare species of flora and fauna.
  • The Silent Valley region is locally known as “Sairandhrivanam”, which in Malayalam means Sairandhri’s Forest.
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