Dry Flies and Surface Tension
 
- Dry
flies represent insects that are hatching,
terrestrials that have fallen into the
water, insects laying eggs, and insects who
have finished their life cycle, die, and
fall into the water. A nymph is a stage in
an aquatic insect's life where they live
under the surface of the water until they
hatch as an adult insect. An emerging
nymph is the stage when the insect tries to
break through the surface film so that it
can shed its exoskeleton and fly off as an
adult. The surface tension is critical
in order to present a dry fly or an emerging
nymph as naturally as possible.
- Lets
examine surface tension. Water molecules
that are on the surface do not have
molecules on all sides. Therefore,
they try to cohere more strongly with those
around them. This forms a surface “film”
which makes it more difficult for an object
to move through the surface than to move
when it is submersed. (GSU)
- Since
dry flies are light in weight and generally
use hollow fibers for extra buoyancy, the
surface tension keeps them on top of the
water. Emerging nymphs are generally tied
with the buoyant fibers toward the top and
little to no fibers down the shank.
This creates a fly that gets trapped in the
surface film.
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