Even in cold weather, by turning rocks over in creeks you can find one the most fearsome freshwater invertebrates in Ohio – the Hellgrammite.

Though they live underwater, they are poor swimmers - but voracious predators. Hellgrammites will capture and eat any creature smaller than themselves.  They hide under rocks at the bottoms of lakes, streams and rivers and catch food with their short, sharp jaws (if handled carelessly, they can inflict painful bites on humans).

They have pincers on the tail end too, which enable them to grab onto rocks in fast-flowing water.

After two or three years of living and growing underwater, Hellgrammites crawl out onto land and pupate. They stay as a pupa over the Winter and emerge in the Summer only to mate. Here’s a pupa that I found under a rock at the edge of a creek.

Upon emerging, they live for only seven days. The winged adult insects are known as Dobsonflies. They are among the largest flying insects in the United States and look like something straight out of a horror movie. Males appear quite fearsome, with gigantic jaws that can be nearly half the length of their body.

Though intimidating, they are unable to harm humans, as they have such poor jaw leverage that they are incapable of biting. Their mandibles are used exclusively during courtship, when males show them off to, and later grasp interested females with them. Dobsonflies don’t eat and die shortly after mating.

The Hellgrammite is an interesting aquatic insect and an intriguing creature to seek out year-round. It goes through two easily recognized stages of life and its behavior and lifestyle in each stage is dramatically different.

Third Eye Herp
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