Order Plecoptera
& Grylloblattodea
Submitted To :
Lect . Abdul Rehman Azam
Submitted By:
Mehwish Manzoor

Order Plecoptera
 Members of this order include: stoneflies.
 Etymology: Plecoptera comes from the Greek words pleco,
which means folded, and Petra, which means wings.This
refers to the hind wings, which lie folded and concealed
beneath the front wings when the insect is not flying.

Meltwater Stonefly

General characteristics:
 long, somewhat dorsoventrally flattened body
 long, multi-segmented antennae
 two long, multi-segmented cerci
 two pairs of membranous wings
 forewings are long and narrow and fold atop one another
when the insect is at rest, concealing the hind wings

Cont……
 hind wings are slightly shorter, but considerably wider than the
forewings
 the hind wing’s anal lobe (see illustration) is pleated, which allows
it to fold beneath the forewings
 crossveins form two rows of “windowpanes” in the middle of each
forewing
 hemimetabolous metamorphosis (egg — naiad — adult)
 Number of recognized species worldwide: 1,500-3,000

Stonefly Nymph

Grylloblattodea
 Common Name: Rock Crawlers / Icebugs
 Greek Origins of Name: Grylloblattodea, derived from the
Greek “gryll” meaning cricket and “blatta” meaning
cockroach, refers to the blend of cricket-like and cockroach-
like traits found in these insects.

characteristics
 Rock crawlers measure 14–30 mm in length, and are elongate
and cylindrical.
 Mouthparts mandibulate, hypognathous
 Eyes are small or absent.
 The head is large, consistent with orthopteroids

Cont…..
 The antennae are filiform, moderate in length, and shorter
than many crickets and cockroaches.
 The legs are unspecialized, and the tarsi have five segments
ending with a pair of claws.
 The body segments are clearly differentiated

Icebug

Development & Distribution
 Development: Hemimetabola, i.e. incomplete
metamorphosis (egg, nymph, adult)
 Distribution: Rare. Found in caves or near ice or snow at
high elevations in mountains of Asia and North
America. Approximately 1 family and 11 species in North
America and 1 family and 25 species worldwide

Fun Facts
 Rock crawlers were first discovered around 1906; the first
formal description of the order was published in 1915.
 With only 25 species described worldwide, Grylloblattodea is
the second smallest order of insects. Mantophasmatodea is
the only order with fewer species.
 Rock crawlers cannot tolerate warm temperatures. Most
species are active below freezing and usually die above 10
degrees Celsius.

Cont…..
 Due to the cold temperature at which they live, growth and
development is very slow. Rock crawlers may require up to
seven years to complete a single generation.
 No grylloblattids have ever been found in the Southern
Hemisphere.

ThankYou
for Listening
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