Hellgrammites At Stroud: ‘King Kong’ Of Water Insects

a close up of a hellgrammite in a red collander

This August 2023, attendees of our ‘Splish Splash’ event hosted at Stroud Preserve braved a rainy forecast to play in Brandywine Creek. Children and parents plunged into chilly waters with nets and magnifying cups to explore under rocks and discover insects living in the creek-bed.  

One of the most exciting discoveries of the day was a macro-invertebrate aquatic insect called a hellgrammite, also known as the ‘King Kong’ of water insects… for good reason! Hellgrammites can grow as long as two to three inches and are the larva of the dobsonfly. Over the course of their lifetime, they will undergo complete metamorphosis before growing wings and spending the latter part of their existence on land.  

Besides being super cool to look at, the sight of this gargantuan water insect is an indicator that the Brandywine hosts clean water fresh enough for these insects to flourish and call home. Because they can survive only in well-oxygenated habitats, the presence of a hellgrammite is a marker of the creek’s health and water quality.  

There is so much to explore and discover across our preserves. Natural Lands aims to keep land open and accessible for all.  

Please explore some of our events open to the public and join us at a preserve today: natlands.org/events.  

You never know what you may discover.