You never know who—or what—you might meet while adventuring around the Upper Delaware River region. While walking on the Roebling Bridge Towpath along the banks of the Delaware River recently, I encountered a creepy-looking critter scuttling along, minding its own business and eager to escape my presence unscathed. 

I recognized the hellgrammite at hand, thanks to an alarming encounter as a child, when one became trapped in my bathing suit during a family tubing trip on the Lackawaxen River. Let’s just say I had no idea at the time that this fearsome-looking creature was not a menace, though you probably couldn’t have convinced me of that then.

A little education can go a long way toward helping us understand—and appreciate—the importance of the animals we share our lives with here—such as hellgrammites. Even the name is unsettling, but in reality, this aquatic insect, which is the larval stage of the dobsonfly, is a bioindicator of good water quality and an important reason to appreciate their presence here.

Don Hamilton, who recently retired from a long and successful career with the National Park Service serving the Upper Delaware Scenic and Recreational River, contributed the following information in a guest column for the River Reporter several years ago.

“Aquatic insects play an important role in the health of the Delaware and other rivers on many levels... they facilitate an efficient transfer of energy and nutrients through various trophic levels of the river’s ecosystem and surrounding environs.” As such, they form an important link in the aquatic food chain, providing sustenance for fish, birds, and mammals.

“Larger aquatic insects such as dobsonflies are unlike most other aquatic insects in that they go through complete metamorphosis, undergoing a pupal stage between the transition from aquatic larvae to flying adults. Larvae in this group that are ready to pupate (known as prepupae) crawl from the water onto the shore, where they may seek shelter under a log or vegetation. In two weeks or less, from this pupal stage emerges a winged adult, with a few days remaining in its life cycle to mate and (if a female) return to the river to lay eggs that will begin a new generation,” wrote Hamilton. 

Learn more about the many interesting species living in our region at the upcoming 2024 Upper Delaware BioBlitz in June at the Highlights Foundation Retreat Center in Boyds Mills, Wayne County, PA.  A BioBlitz is an event where biology experts and volunteers gather to collect, identify, and catalogue every living thing on a demarcated property in a 24-hour period.

Teams focus on categories of life such as aquatic macroinvertebrates, birds, plants, fish, fungi, reptiles and amphibians, terrestrial invertebrates, mammals, mosses and lichens. 

On Saturday, June 29 from 10 a.m. to 4 p.m., the public is invited to come and meet the scientists, see what they have collected, learn about their work, go on walks and participate in workshops. There will be art activities and performances for children to experience science in different ways. Visit www.upperdelawarebioblitz.com to learn more.