| Stonefly
Nymph
Stoneflies are insects often found resting on stones.
What they look like:
Stonefly nymphs are often confused with Mayfly
nymphs. Stonefly nymphs have two long tails or cerci
(sir-key), whereas Mayfly nymphs have three long tails.
The cerci are sense organs but also help the insect to
move. Stonefly nymphs have tubes of
thread-like gills on their underside, wing pads and
antennae (feelers). Each leg has two claws that are
used to cling to rocks or sticks. Their bodies are streamlined
so they don't get swept away by the water current.
Size:
7-12 mm long.
Where they live:
Stonefly nymphs live under stones in fast-flowing streams
cooler than 25 degrees Celsius. Mountain streams are
a good habitat for them. You may also find the nymphs
on top of stones, or on the submerged wood and leaf
litter in streams.
What they eat:
Most Stonefly nymphs eat dead plants and algae. Other
stonefly species (predators) stalk their prey and are
carnivorous (eating other animals).
Pollution
tolerance: Very sensitive, rating 10.
Stonefly nymphs are very sensitive to low levels
of oxygen in water. They prefer cool water as it
dissolves oxygen more easily than warm water. |
What’s interesting about
the Stonefly Nymph?
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