The Hellgrammite is the larva stage of life of the Dobsonfly. I am sure that if you have
ever caught any nymphs you have seen the hellgrammite. I am also sure that if you
have ever picked one up you quickly learned one difference in a mayfly or stonefly
nymph and the hellgrammite. They can and will bite and pinch.
These flies deposit their eggs on the bottom side of leaves and stems of the bushes
and trees. The eggs hatch into larvae and fall off into the water where they live until
they hatch. The larvae are predators that eat other insects. The adult Dobsonfly is
a very large fly that looks a lot like a stonefly. They are nocturnal, so it is doubtful
you will see them very often in the daylight hours. The adults only live a few days
during which time they mate and deposit their eggs in the darkness.
The larvae are readily eaten by trout as well as smallmouth bass. I mention
smallmouth because the dobsonfly tends to dwell in slightly warmer water or water
that is marginal for trout. Most all the small streams at the mid to lower elevations have
fairly large populations of the larvae.
Hellgrammites can be found in the riffles. The fishflies are more frequently
found in the eddies and backwater or slow water areas of the streams. Fish the
imitation exactly like you would a clinger mayfly nymph imitation. You need to keep
the fly on the bottom by weighting it down. Most of the time an up, or ab up and across
presentation works best. Short-line nymphing or "high stickin" also work with the
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