Download Stoneflies - walidandbrandon

Stonefly nymphs eat dead plats and algae,
they also feed on organic and vegetable
matter found in the stream substrate,
many species feast on leaves falling from
streamside trees . Some species stalk
their prey and are carnivorous eating other
animals, feeding on mayfly nymphs and
other insect larva. Many of stonefly adults
do not eat, but those that live as adults
longer do eat vegetation, pollen or nectar.
Most female stoneflies skim the surface of the stream,
dipping their abdomens in the water and releasing their
eggs. Others will actually crawl to the bottom of the
stream and then release their eggs on submerged
objects. Stoneflies are very clumsy fliers and during the
egg releasing procedure will cause quite a fluttering and
splashing on the water surface which immediately
attracts the attention of hungry fish especially
steelhead. Highly ornamented eggs may hatch quickly or
undergo long diapause. The nymphs grow through many
instars (12 - 23). The length of the life cycle is 1 to 4
years. Mature nymphs move to shore and climb out of
the water (mostly at night) before the final molt. Adults
live for a few days to few weeks among shoreline
vegetation or rocks and they feed little, if at all. Males
attract mates by drumming, and mate while alighted.
Females lay the eggs on or above the water. The eggs
separate and sink to the bottom.
Well known with many faunal
treatments and revisions available.
Currently a popular group receiving
much attention, which is resulting in
many new discoveries and taxonomic
changes. Many current names
represent elevations in former
ranks. Males, females, eggs, and
nymphs are frequently identifiable
to species.
Two pairs if present.
Both pairs membranous and clear.
Most species have moderate number of wing cross-veins that form
long rectangular cells.
Few species have numerous cross-veins and cells.
Hindwings are shorter and wider than the forewings.
At rest, wings overlap and are held flat over body or often curving
around the abdomen.
Generally cover the abdomen though a few species have short wings.
Harmful: A Stonefly nymphs bite totally drains the
blood of an adult human
Beneficial: most stonefly adults have not
developed mouthparts and cannot bite.
Plecoptera, or stoneflies, is a small order of hemimetabolous insects: according
to our data, more than 3,497 species have been described so far in the world.
The total number of species has enormously increased in the last 30 years
(2,000 species estimated in 1976) and, if the trend continues, then it will nearly
double in the near future. The order is divided into the suborders Arctoperlaria
and Antarctoperlaria, and includes 16 families: 12 arctoperlarian and 4
antarctoperlarian. The Arctoperlaria account for a total number of 3,179
species, and Antarctoperlaria, only 318 species. The total number of genera is
286. We give in this article the estimated number of species for each family.
The fauna and diversity of stonefly in North America (650 species reported)
and Europe (426 species) are best known. Nevertheless, in the last 25 years, a
mean of 2.6 Plecoptera species per year were described in Europe. Stoneflyfaunas of Australia (191 species, Tasmania included) and New Zealand (104
species) are relatively well-known, while our knowledge of the Plecoptera of
Central and South America (95 and 378 species respectively) is poor and still
not representative of the real diversity. Africa has a reduced stonefly fauna
(126 species). Asian stonefly diversity (approximately 1,527 species) is much
greater than that of Europe or North America despite the fact that, except
for Japan and Asiatic Russia that have been well studied, our knowledge of the
remaining Asiatic areas is extremely poor. Even though our data indicate the
Holarctic Region as the diversity hot-spot for the order, the analysis of the
specific diversity divided by family suggests also an important role of tropical
stoneflies.
Stoneflies have a generalised
anatomy, with few specialised
features. they have simple mouth
parts with chewing mandible, long
multi segmented antennae, large
compound eyes and have two or
three ocelli. the legs are strong
with each ending in two claws. the
abdomen is relatively soft, and
include remnants of the nymphal
gills even in the adult. Both nymphs
and adults have long paired cerci
connecting from the tip of their
abdomens.
STONEFLY FACTS
Like many aquatic insects,
stonefly naiads need clean
water to live. Because of this,
scientists can tell if a stream
is polluted or not based on
whether stonefly naiads are
present. Read more about
using insects to determine
water quality.