The Intrepid Nepid
Nathan Varley
When I’m out collecting waterbug samples I’m always delighted to find one of these beasts.
They are known as Nepids, as they belong to the Nepidae family. Nepids have two main body types, skinny ones, commonly referred to as needle bugs, in Sydney from the genus Ranatra (yawn) or a broader more leaf like body shape which are known as water scorpions Laccotrephes tristis (yeah!!). Both are awesome to see, but the water scorpion, for me, looks more impressive.
The long tube out the back is not a “stinger” as is the case in terrestrial scorpions, but functions as a breathing snorkel. This allows these predators to sit submerged, camouflaged amongst the waterway’s vegetation, until the unsuspecting prey swims past. Nepids are not setting any world records when it comes to swimming, however they have excellent eye sight and their modified front legs are super quick at striking out to catch prey as it swims past. The unsuspecting prey is snatched from the water and quickly pierced with their proboscis.
I was lucky enough to have the water scorpion pose for me at Mill Creek, south of Sydney, while the needle bug was found upstream from Madden’s falls, near Darks Forest.
Nathan Varley is an aquatic ecologist with Sutherland Shire Council with a keen interest in freshwater macroinvertebrates.