Exopterygote

Exopterygote Orders
(Odonata, Orthoptera, Dictyoptera,
Isoptera, Thysanoptera and Hemiptera)
@Bhubanananda Adhikari

Odonata
(Dragonfly, Damselfly)

Odonata (Odon : Tooth)
• Medium to large sized insects. They are attractively
coloured.
• Head is globular and constricted behind into a petiolate
neck.
• Compound eyes are large. Three ocelli are present.
• Mouthparts are adapted for biting. Mandibles are
strongly toothed Lacinia and galea are fused to form
mala which is also toothed.
• Wings are either equal or sub equal, membraneous;
venation is net work like with many cross veins.
• Wings have a dark pterostigma towards the costal apex.
Wing flexing mechanism is absent.
• Legs are anteroventrally placed. They are suited for
grasping, holding and conveying the prey to the mouth.
General
Characters

Odonata
• Forward shift of leg attachments allow easy transfer of
prey items to mouth in flight. Legs are held in such a
way that a basket is formed into which the food is
scooped.
• Abdomen is long and slender.
• In male gonopore is present on ninth abdominal
segment. But the functional copulatory organ is present
on the second abdominal sternite.
• Before mating sperms are transferred to the functional
penis.
• Cercus is one segmented.
• Metamorphosis is incomplete with three life stages.
The naiad is aquatic.
General
Characters

Odonata
• Adults are aerial predators. They are able to
catch, hold and devour the prey in flight.
Naiads are aquatic predators.
• Dragonflies and damselflies can be collected
with an aerial net. Naiads can be collected
from shallow fresh water.
• Two suborders
i. Anisoptera (Dragonfly) : Unequal wings
ii. Zygoptera (Damselfly) : Equal wings
Importance
and
Classification

Odonata
Adult
Anisoptera (Dragonfly) Zygoptera (Damselfly)
 Strong fliers with unequal wings (Hindwings
basally broader than forewing)
 Weak fliers with equal wings
 Wings are broadly attached  Wings are petiolated and narrowly attached
 Venation not similar in both wings  Identical venation
 Wings spread laterally at rest  Wings held at an angle above abdomen
 Holoptic eyes (Large eyes meet mid dorsally)  Dichoptic eyes (Eyes are separated)
 Total 3 abdominal appedages : 2 anal cerci
(superior anal), 1 epiproct (inferior anal)
 Total 4 abdominal appedages : 2 anal cerci
(superior anal), 2 paraproct (inferior anal)

Odonata
Dragonfly wing pattern
Damselfly wing pattern
Dragonfly holoptic eyes
Damselfly dichoptic eyes

Odonata
Naiad
Anisoptera (Dragonfly) Zygoptera (Damselfly)
 Stout Robust  Slender and Fragile
 Internal Rectal Gill  External Caudal Gill
 Jet propulsion mechanism
present (Eject themselves
by forceful ejection of
water through anus from
rectum)
 Jet propulsion absent
Dragonfly naiad
Damselfly naiad

Orthoptera
(Grasshoppers, Locust, Katydid,
Cricket, Mole cricket)

Orthoptera (Ortho: Straight)
• Syn : Saltatoptera, Saltatoria
• They are medium to large sized insects. Antenna
is filiform.
• Mouthparts are mandibulate.
• Prothorax is large. Pronotum is curved, ventrally
covering the pleural region.
• Hind legs are saltatorial.
• Forewings are leathery, thickened and known as
tegmina. They are capable of bending without
breaking.
• Hindwings are membranous with large anal
area. They are folded by longitudinal pleats
between veins and kept beneath the tegmina.
General
Characters

Orthoptera
• Cerci are short and unsegmented.
• Ovipositor is well developed in
female.
• Metamorphosis is gradual.
• In many Orthopterans the newly
hatched frist instar nymphs are
covered by loose cuticle and are
called pronymphs.
• Specialized stridulatory (sound-
producing) and auditory (hearing)
organs are present.
General
Characters

Orthoptera
Basic Difference between 2 Suborders
Caelifera Ensifera
 Antenna is short with less than 30
segmented
 Antenna is long with more than 30
segmented
 Tympanum on the lateral side of first
abdominal segment
 Tympanum on the fore tibia
 Mandibles are specialized for consuming
monocot foliage
 Feed on dicot plants
 Diurnal  Nocturnal
 Rely on jumping to escape from predators  Rely on crypsis
 Eggs are laid in groups in soil inside shallow
burrows
 Eggs are singly inserted into plant tissue or
soil

Orthoptera
Caelifera Ensifera
Classification
Acrididae
Tettigonidae Gryllotalpidae
Gryllidae
2 Sub orders
Antenna > 30
segmented
Antenna < 30
segmented
Short horned
grasshopper,
Locust Long horned
grasshopper, Katydids,
Bush Cricket
Crickets Mole Crickets

Acrididae
• Short horned grasshopper and locust
• Short antenna
• 3 segmented tarsus
• Short horny ovipositor
• Tympanum on either side of abdominal
segment
• Sound production is femero alary *
*A row of peg like projections on the
inner side of hind femur rubbed against
radial vein of tegmen
S.O : Caelifera

Acrididae
• Locusts are polymorphic short horned
grasshopper
• More than one morphological forms
with in the same species.
• Solitary Phase and Gregarious phase
• Central locust warning organization at
Faridabad
S.O : Caelifera
Locust
Solitary Phase Gregarious Phase
 Live individually  Live in group
 Difficult to locate  Easy to locate
 Grey or green  Pink with yellow band
(immature) total yellow
(Matured)
 Long hind femur  Short hind femur
 Short tegmina  Long tegmina
 High fecundity  Low fecundity
 Less destructive  Highly destructive

Tettigonidae
• Long horned grasshopper, Katydids, Bush Cricket
• Long antenna (longer than body)
• Sword like ovipositor
• Pair of Tympanum in each foretibia
• Sound production Alary type *
• * Thick region of hind margin of forewing
(Scrapper) rubbed against row of teeth on
stridulatory vein (File) on ventral side of another
forewing
S.O : Ensifera

Gryllidae
• Cricket
• Long antenna
• Needle like ovipositor
• Forewings are abruptly bent down to cover
side of body. Hind wings are acuminate
produced into a long processes
• Pair of Tympanum in each foretibia
• Sound production Alary type *
• (Males stridulate during night)
S.O : Ensifera

Gryllotalpidae
• Mole cricket
• Found inside burrows
• Reduced eyes, elongated pronotum
• Fossorial forelegs
• Hindwings are extended beyond the tegmina
(forewing)
• Special stridulatory structures absent.
Humming sound by rubbing of forewing.
• Vestigeal ovipositor
• Pair of Tympanum on under surface of tibia
• Gryllotalpa africana
S.O : Ensifera

Dictyoptera
(Cockroaches, Preying mantids)

Dictyoptera (Dictyon: Net work)
• Syn : Oothecaria, Blattiformia
• Hypognathous head with filliform antenna and
chewing type mouth.
• Cursorial leg in Cockroach. Last two pairs leg are
ambulatorial in mantids and fore legs are
raptorial. Tarsus 5 segmented
• Fore wings are tegmina (leathery), Hind wings
large membranous folded fan like kept beneath
the fore wing.
• Short many segmented cerci.
• Eggs contained in Ootheca in cockroach and egg
case in mantids.
• Hemimetabola (Gradual metamorphosis : pauro
metabola)
General
Characters

Dictyoptera
Basic Difference between 2 Suborders (Blattaria,
Mantodea)
Blattaria
[Family: Blattidae]
Cockroach
Mantodea
[Family: Mantidae]
Preying mantids
 Head is not mobile in all
direction as it is hidden by
shield like pronotum
 Head is mobile in all
direction as it is not covered
by pronotum (elongated)
 2 fenestrae (degenerated
ocelli)
 3 ocelli
 All legs cursorial  Foreleg raptorial, other are
ambulatorial

Dictyoptera
Basic Difference between 2 Suborders (Blattaria,
Mantodea)
Blattaria
[Family: Blattidae]
Cockroach
Mantodea
[Family: Mantidae]
Preying mantids
 Gizzard with chitinous teeth  No chitinous teeth in gizzard
 Female does not devour
male
 Female often devours the
male during mating
 Eggs inside ootheca  Eggs in egg case
 Nymps are not cannibalistic  Cannibalistic nymph
 No mimicry  Mimicry
 Omnivorous  Carnivorous

Dictyoptera
• Cockroaches are found in household,
deadwood and preying mantids are
found in outdoors.
• Cockroaches feed on food stuff, clothes
and paper. Impart foul smell to food by
contaminating with excreta. So they are
harmful (American cockroach:
Periplaneta americana).
• Preying mantids are predators on
moths, flies and grasshoppers. They are
beneficial insects (Mantis religiosa)
Economic
importance

Thysanoptera
(Thrips)

Thysanoptera (Thysano: Fringe)
• Syn : Physopoda
• Hypognathous head
• Short antenna (4-9 segmented)
• Rasping and sucking mouth (3 stylets, Right
mandible is absent. mouthparts asymmetrical).
• Wings either absent or long, narrow and fringed
with hairs.
• They are weak fliers and passive flight in wind.
• Tarsus is with one or two segments. At the apex of
each tarsus a protrusible vesicle is present.
• Abdomen is often pointed.
• An appendicular ovipositor may be present or
absent.
• Intermediate metamorphosis (Prepupa stage found)
General
Characters

Thysanoptera
Basic Difference between 2 Suborders
Terebrantia
(Fam: Thripidae)
Tubulifera
 Female: appendicular
ovipositor (saw like)
 Ovipositor absent
 Abdomen end not
tube like
 Abdomen end tube
like
 Wing venation  No Wing venation
 3rd instar: Prepupa,
4th instar: Pupa
 3rd instar: Prepupa,
4th ,5th instar: Pupa
 Crop pest  Not crop pest
Terebrantia
Tubulifera

Thysanoptera
• Most of the thrips species belong to the family
Thripidae and are phytophagous. They suck the
plant sap.
• Some are vectors of plant diseases.
• Few are predators. e.g. Rice thrips:
Stenchaetothrips biformis is a pest in rice
nursery.
i. Thrips tabaci : pest of onion, melon, cotton
ii. Scirtothrips citri : pest of citrus
iii. Frankliniella tritici : pest of flowers, wheat
Economic
importance

Isoptera
(Termites, White ants)

Isoptera (Iso: Equal)
• Syn : Termitina, Termitida, Socialia
• Greyish white soft bodied insects weak
sclerotization
• Compound eyes in alate (Winged) form and
absent in apterous (wing less) forms
• Short and moniliform antennae
• Biting and chewing mouth parts
• Two pairs of identical wings, which are
membranous and semitransparent without
distinct venation
• They are apterous (wingless), brachypterous
(Short or rudimentary wing) or winged.
• Veins near costal and anal margin are distinct
General
Characters

Isoptera
• Wings are flexed over abdomen at rest. They are
extended beyond abdomen
• Wings are present in sexually matured form during
swarming season
• Legs short and stout. Tarsus usually 4 segmented.
• Some species constructs earthen tubes between the
soil and wood above ground;
• Anal cerci short or very short.
• Metamorphosis is simple or incomplete.
• The cellulose in termites food is digested by the
symbiotic association of a protozoa living in the
digestive tract of the insect. But in higher termites
like termitidae family, cellulose digested in gut
without protozoal association
General
Characters

Isoptera
• Social insects live in colonies
• Salivary glands are well developed.
• Rectum is distended forming rectal
pouch to accommodate large number
of intestinal symbionts
• Fat body in male and nonreproductive
females.
• Soil inhabiting termites construct
earthen mounds called termitaria
• Food sharing (Trophallaxis) either by
mouth-to-mouth (Oral trophallaxis)
and anus-to-mouth (Anal trophallaxis).
• Nature scavengers
General
Characters

Isoptera
Caste System
Each group of individuals performing the
same function is called caste
Non reproductive
Primary
Reproductive
Supplementary
Reproductive
Reproductive
King
Queen
Workers
Soldiers
Nymph with
wing bud
Nymph without
wing bud
 Sexually sterile
 Apterous (wing less)
 Reproductive
organs atrophied
 Blind
 Dark sclerotized body
 Compound eyes, wings
well developed
 Pale body with poor
Sclerotization
 Compound eyes, wings
not well developed
 Replace the primary
reproductive when
they die

Isoptera
• Intermittently fertilizes the queen
• Helps the queen in construction
of nuptial chamber and in rearing
the first brood
King
• Single queen
• After fertilization queen attains
obesity in abdomen, ovaries
enlarged, developed fat bodies
called physogastry
Queen

Isoptera
• Soft unpigmented body
• Well developed mandibles and salivary glands
• Excavate earth and build earthen mounds with
soil and saliva
• Repair the termitaria
• Go out for foraging
• They feed the king, queen and soldiers.
• Care for eggs and young ones
Workers

Isoptera
• Two types of soldiers (Mandibulate and
Nasute)
• They defend the colony
• In mandibulate soldiers large and well
sclerotized head with well developed
mandibles
• In nasute soldiers head is drawn into
nozzle shaped projection at the tip of
which frontal gland opens. Defence by
glandular secretion
Soldiers

Isoptera
• Living place of termite
• Soil inhabiting termites build mounds
below ground or above ground with soil,
saliva and excreta
• Gives protection and temperature
regulation
• 3 structures found inside termitaria
1) Royal cell : King, queen dwelling place
2) Fungal garden: Disributed around
royal cell
3) Forage tunnel: Tunnels to different
directions along with termites , other
fauna called termitophiles also found
Termitaria

Hemiptera
(True bugs)

Hemiptera (Hemi: Half)
• Syn : Rhynchota
• Opisthognathous head
• Piercing and sucking mouth having 4 stylets (2
mandibular, 2 maxillary) inside labial groove forming
food canal and salivary canal. Epipharynx and
hypopharynx are absent.
• Mesothorax represented dorsally by scutellum
• Forewings are either uniformly thickened or basally
coriaceous distally membranous.
• Hemimetabola (Gradual metamorphosis)
• Alimentary canal modified (filter chamber)
• Salivary glands universally present
• Extra oral digestion widspread
General
Characters

Hemiptera
Basic Difference between 2 Suborders (Heteroptera, Homoptera)
Heteroptera (Hetero: different) Homoptera (Homo: uniform)
 Horizontal head , not touched by the base of the forelegs.  Deflexed head touched by the base of the forelegs.
 Beak arises from anterior part of head  Beak arises from posterior part of head
 Enlarged pronotum  Small and collar like pronotum
 Scutellum well developed  Scutellum not well developed
 Forewings Hemelytra (sclerotized only basal half and
apical portion membranous)
 Forewings have uniform texture and harder than hind
pair
 Wings held flat over back at rest, both side overlap on
abdomen
 Wings held roof like over back, don’t overlap
 Honeydew secretion not common  Honeydew secretion common
 Repugnatorial/odoriferous/scent glands  Wax glands
 Herbivorous, predaceous or blood sucking  Herbivorous
 Terrestrial and aquatic habitat  Terrestrial

Coreidae
• Squash bug/ leaf footed bug
• Membrane with many branching veins
arising from a transverse vein
• Stink glands inside metathorax and opening
of glands on side of thorax between middle
and hind coxae.
• Emit bad odour
• Hind tibia and tarsi expanded leaf like
• Nymph and adult suck sap from pods of
pulses
• Pod bug : Riptorus sp.
S.O : Heteroptera

Pentatomidae
• Stink bug/ Shield bug
• Scutellum prominent shield like
• Adults and nymphs produce foul
odour from stink glands
• Stink glands located in metathorax
and abdomen
• Phytophagous/ Predaceous
• Green stink bug (pest of millet) :
Nezara viridula
S.O : Heteroptera

Cimicidae
• Bed bugs
• Dorsoventrally flattened body with oval outline
and deeply notched thorax.
• Reduced hemelytra and atrophied hind wings
• Stink glands are present in the dorsal surface of
first three abdominal segments.
• Male insects pierce the integument of female to
inject the sperm into haemocoel of female which
is known as traumatic insemination.
• They are blood sucking ectoparasites on birds and
mammals.
• They hide during day time and emerge at night to
take blood meal.
• Cimex lectularis, Cimex hemipterus
S.O : Heteroptera

Pyrrhocoridae
• Red bugs/ Stainers
• Exhibit red and black colourations.
• Ocelli absent.
• More branched veins present in hemelytra.
• Coxa is rotatory and tarsi 3 segmented with
pulvilli.
• An important pest species in this family is the
cotton stainer, Dysdercus cingulatus which is a
serious pest of cotton. It stains the cotton fibre
by its feeding and greatly reduces the
marketability.
S.O : Heteroptera

Lygaeidae
• Seed bug/ Chinch bug
• Cuneus absent in hemelytra
• Membrane has a few irregular veins arising
from a transverse basalvain
• Nymph and adult suck sap from injured
seeds or already opened bolls
• Dusky cotton bug : Oxycarenus sp.
S.O : Heteroptera

S.O : Heteroptera
Gerridae
(water strider, pond skater)
Foreleg raptorial, middle leg for
pushing and hind leg for
steering. Legs with non wetting
hairs. Skate on water surface
Reduviidae
(Assassin bug, Kissing bug)
3 segmented proboscis in
elongated head. Lateral margins
of abdomen extend beyond
wings
Tingidae
(Lacewing bug)
Pronotum has lace like lateral
expansions. Forewings have
lace like markings. Nymphs
show difference from their
adults.

S.O : Heteroptera
Miridae
(Plant bugs, Leaf bugs)
forewings tilted at the
distinct angle posterior
to abdomen.
Tea mosquito bug
Anthocoridae
(Flower bugs)
black with white
markings. Forewings
possess embolium
Nepidae
(water scorpion)
Raptorial forelegs, and
ambulatorial middle
and hind legs. A long
caudal breathing tube
formed by cerci
Belostomatidae
(Giant water bug)
Antenna concealed in ear like
pockets. Raptorial forelegs
and swimming posterior legs.
terminal breathing tube. In
some species eggs are laid on
the back of males

S.O : Heteroptera
(C: Corium, CL: Clavus,
CU: Cuneus, E: embolium)
[I: Lygaeidae, II: Miridae,
III: Anthocoridae]

Cicadellidae
• Leaf hoppers/ Jassid
• Wedge shaped body/ attractively coloured
• Hind tibia have double row of spines
• Ovipositor suited for lacerating plant tissue
• Suck sap and transmit disease
• Green leaf hopper: Nephotettix virescens
S.O : Homoptera

Delphacidae
• Plant hoppers
• Large mobile flattened spur at apex of hind
tibia
• Brow plant hopper: Nilaparvata legens
• Causes hopper burn transmit viral disease
S.O : Homoptera

Aphididae
• Aphids/Plant lice
• Pear shaped body
• Apterous and alate forms present
• Pair of cornicles on dorsum of 5th
or 6th abdominal segment
• Excrete honeydew and sooty
mould fungus grow
• Parthenogenetic reproduction
• Suck sap and transmit disease
• Aphis gossypii
S.O : Homoptera

Coccidae
• Scale insects
• Sexual dimoprphism
• Males are gnat like one pairs of
wings hind wings are halteres
• Females have distinct body
segments and body wall covered by
waxy coatings. Wingless leg less
suck sap
• Coccus viridis
S.O : Homoptera

Pseudococcidae
• Mealybugs
• Body oval shape
• Segmentation distinct
• Body covered by long radiating
thread of mealy secretion
• Functionallegs present in all instars
• Wings absent
• Nymphs and adult suck the sap
• Pseudococcus longispinus
S.O : Homoptera

Lophopidae
• Aeroplane bug
• Head is produced into snout
• Hind trochanter backward
• Nymph adult suck sap
• Sugarcane pyrilla : pyrilla purpusilla
S.O : Homoptera

Aleyrodidae
• Whitefly
• Resemblance with tiny moth
• Wings with mealy white powdery wax
• Wing venation reduced
• Vasiform orifice at last abdominal tergite
• Immature instars sessile, scale like
• Approaches to holometabolous
• Bemisia tabaci
S.O : Homoptera

@Bhubanananda Adhikari S.O : Homoptera
Cicadidae
(Cicada)
Transparent wings. Eggs inserted
into tree twigs. Males have
sound producing mechanism.
Nymph dropto ground. Nymphal
anterior femurs with spines for
digging
Membracidae
(Tree hopper, Cow bug)
Large pronotum covers head
also extended backward over
abdomen
Cercopidae
(Spittlebug, Frog hopper)
Adults resemble tiny frogs. Hind
tibia with 1-2 lateral spines.
Nymphs are in froth.

Psyllidae
(Jumping plant lice)
Small active insect resemble
minute cicada. Move actively by
leaping and flying
Diaspididae
(Armoured scale)
Female lacks antenna, legs
wings. Body covered by hard
shells.
Kerridae
(Lac insects)
Females without legs, wings
antenna. Body is irregularly
globular and enclosed in a
resinous cell. Laccifer lacca.
Dermal gland secretion

Exopterygote

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