for 2nd year biology students

1. MANSOURA UNIVERSITY
INSECT MORPHOLOGY
For 2nd year biology
By
Dr. Zeinab Abu-Elnaga
•Entomology 2014 zenab_77@mans.edu.eg
Zoology Department, Faculty of Science http://zaboelnaga.synthasite.com
Dr.ZAbu-Elnaga

2. COURSE OUTLINES
o General introductory lecture.
o External body morphology of insects and its
modifications
 Body apertures
 The head capsule
 Structure
 Cephalic appendages
1. The antennae
2. The mouth parts
 The thorax
1. The wings
2. The legs
 The abdomen
1. The cerci
2. The genitalia
3. The styli
4. Stinging apparatus
5. Springing apparatus
Dr.ZAbu-Elnaga

3. INSECTMORPHOLOGY
Dr.ZAbu-Elnaga

4. GENERAL LECTURE
INSECTS
 Systematic Position:
Insects are members of one of the biggest classes of the….. Phylum:
Arthropoda (Nonchordata with jointed legs)
Class: Insecta (Hexapoda) (i.e. =six-legged or possess 3 pairs of legs) .
 General Characters:
A- Characters common between insects and other arthropods:
 Triploblastic coelomate with bilateral symmetry
 Segmented body and jointed appendages.
 Exoskeleton.
 Locomotory system with skeletal muscles.
 3 pairs of peristomal appendages.
 Sense organs, Antennae (tactile & olfactory) & compound eyes.
 Mostly Dioeceous (sexes separate)
 Heamolymph (corresponding to both blood &lymph of vertebrates).
 Blood circulation is open type.
 Undergo metamorphosis (post-emberonic development).
Dr.ZAbu-Elnaga

5. B- distinguish characters for insects:
 Three regions body (head [cephalization], thorax, & abdomen).
Only one pair of antenna, no antennules.
Sessile compound eyes, (stalked in Arthropods).
Peristomal appendages (mouth parts).
 Thorax (pro-, meso-, & metathorax), each one with pair of legs.
 Wings (meso- & metathorax).
 Adults have no abdominal legs.
 The space between the viscera is filled by fat tissue.
 Tracheal system is well developed, and gills, but no lung books.
 Excretion via malpighian tubules.
Dr.ZAbu-Elnaga

6. ATTRIBUTESOFSURVIVALANDDOMINANCEININSECTS
 Structural
 Size & shape
 The Exoskeleton
 Advanced locomotory organs
 The mouth parts
 Central nervous system
 The reproductive capacity
 The digestive system
 The fat tissue
 Behavioral
 Oviposition hapits
 Protection of quiescent stages
 Periodicity of activity
 Hibernation & diapause
 Feeding habits
 Mimicry & protective coloration
 Biological
 Diversity of diet
 Modes of reproduction
 Life cycle duration
 Metamorphosis
 parasitism
Dr.ZAbu-Elnaga

7. ECONOMIC IMPOTENCE OF INSECTS
 Blood sucking insects (mostly
temporary ecto-parasites on
man or permanent ecto-
parasite).
 Disease transmission
 Myasis to man & animals
 Spoils our food & drink.
 damage of cloths & furniture
 Caused by insects which
infest crop plants & beneficial
animals.
 Plant pests: locusts, larvae of
many moths, thrips, fruit
flies, ……..ect.
 Animal pests: warble flies
attack sheep & cattle, causing
decreased efficacy, milk, &
flesh…….
Direct Indirect
A-Injurious insects
Dr.ZAbu-Elnaga

8. ECONOMIC IMPOTENCE OF INSECTS
 Source of useful materials as
food, (bees, Aphids “honey
dew”, fried locusts, eggs of
big insects,…….. ect.)
 clothing (salivary secretions
of silk worms)
 Industry useful (natural dyes
& inks).
 Pharmaceutical materials.
 Cross pollination.
 Improvement of soil properties
(ground beetles).
 Source of food for birds &
fishes, used, in turn food for
man.
 Discovery of juvenile hormone.
 Some of them used as
biological control agents.
Direct Indirect
B- Benefits of insects
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9. INSECTMORPHOLOGY
Dr.ZAbu-Elnaga

10. THE HEAD REGION & ITS APPENDAGES
o Insects have a distinct and well developed head
region = Cephalization.
o unsegmented, but it actually consists of a number
of fused segments.
brain
Mouth
parts
antennae
Compound
eyes
Dr.ZAbu-Elnaga

11. THE HEAD CAPSULE
 Corresponds to the cranium of vertebrates.
 The typical structure evident in locusts & cockroaches.
Dr.ZAbu-Elnaga

12. POSITIONS OF THE HEAD
 Pro-gnathous: head extended
longitudinally with body axis
(m.p are pointed forward,
Weevils)
 Hypo-gnathous: head
perpendicular to longitudinal
body axis (m.p pointed
downwards, Locust)
 Opitho-gnathous: head bent
underneath thorax during rest
(m.p pointed backwards, Aphids)
Dr.ZAbu-Elnaga

13.  Difintion: pair of jointed segments on front region of insects, mostly located
within socket, & its surface carries numerous fine hairs.
Function: tactile & olfactory organs (touch & smell respectively),moreover,
in mosquito it was for hearing (auditory).
 Typical structure: three main regions:
1. Scape: basal part articulates with head capsule, contains one
segment almost, cylindrical in shape & movable in all directions.
2. Pedicel: short piece, connected to scape via memberanous narrow
ring, for bending.
3. Flagellum: long estpart, many sub-segments, flexible, articulating
basically with pedicle.
Dr.ZAbu-Elnaga

14. TYPESOFANTENNAE
 Setaceous
 Filiform
 Moniliform
 Serrate
 Capitate
 Lamellate
 Aristate
 Pectinnate
 Bipectinnate
 Plumose
 Pilose
 Clavate
 Geniculate
 Stylate
 flate
Dr.ZAbu-Elnaga

15. TYPESOFANTENNAE
 Setaceous: the subsegments of flagellum, tapering terminally, with seta
shape (cockroach).
 Filiform: the flagellum subsegments alomost equal in size, rod shaped, with
blunted end (locust)
 Monliform: the subsegments like beads of necklace (white ant)
 Capitate: the terminal sub-segments enlarge suddenly, cap shaped (flour
beetles).
 Clavate: with large diametered subterminal segments, like knob (butter
flies)
 Pectinnate: each sub-segment carry a thin process on one side, comp
shaped (♀ moths)
 Bipectinate: comp on both sides (♂ moths).
 Lamellate: leaf like subsegments, overlapping each other as a fan (Scarab
beetle).
 Geniculate: angled short flagellum, elbow-shaped (honey bee).
 Plumose: setaceous type flagellum, but carring tufts of long hairs on both
sides, feather shaped (♂ mosquito)
 Pilose: hairs shorter & less than plumose (♀ mosquito)
 Aristate: short, rod shaped & unsegmented flagellum, carries a thread like
process called arista covered with hairs (house flies)
 Stylate: blade like subsegments with pointed apor (Tabanus fly)
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16. INSECTMORPHOLOGY
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17. THE MOUTH PARTS
•Typically evident in cockroach.
•Modification is a functional adaptation
-By reduction of un-needed parts
-Enlargement of the impotent parts or change in its shape
-Development of accessory parts
Dr.ZAbu-Elnaga

18. M. P. OF BUTTERFLY (SUCKING TYPE)
 Modifications according to functional
adaptation.
• Reduction of –Labrum
• Absence of –mandible & hypoharynx.
• Labium represented only by palps (tactile)
• Maxillae fused together & modified into a
sucking proboscis (the functional organ).
 Proboscis: retractile, tubular, &
developed from the two galeae by its
elongation and rolling into a semi-tube
within inter-locked hooks.
Dr.ZAbu-Elnaga

19. M.P.OFBUTTERFLY(SUCKINGTYPE)
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20. M. P. OF HONEY BEE WORKER(BITING LAPPING TYPE)
 Reduction of hypopharynx & labrum.
 Modifications
- Mandibles: 2 flattened rectangular
plates, no teeth, no molar (used in
cutting soft wax).
- Maxillae: cardines rod shaped, stipi
fused to form lorum. The galeae
enlarged sheath. Lacinia, a small lobe
at the base of the galea.
- Labium: tongue-like proboscis. Fused,
extended & rolled glossae.
Dr.ZAbu-Elnaga

21. M.P.OFHONEYBEEWORKER(BITINGLAPPINGTYPE)
Honey bee feeding
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22. Dr.ZAbu-Elnaga

23. MOUTH PARTS OF ♀ MOSQUITO
(PIERCING-SUCKING TYPE)
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24. ♀ ANOPHELES MOSQUITO
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25. MOUTHPARTSOF♀MOSQUITO(PIERCING-SUCKINGTYPE)
 Modifications:
 Labrum-Epipharynx: elongated flap roofing the
Proboscies & covering the underlying mouth
parts.
 Mandibles: pair of thin, hollow long bristle, with
pointed sharp ends. Adapted for piercing blood
vessels & sucking their contents.
 Hypopharynx: a sword-shaped structure
extending between the mandibles & underneath
the labrum-epipharynx. It has sharp edges for
tearing the skin.
 Maxillae: a pair of styles with serrated ends for
scratching the skin (modified galea)
 Labium: elongated, thick walled (protective
sheath for the rest parts)
Dr.ZAbu-Elnaga

26. MOUTH PARTS OF ♂ MOSQUITO
 Not blood sucker (no mandibles)
Maxillae (greatly reduced)
Hypopharynx: fused with labium
Maxillary palps (4 segments “club-shaped”)
Don not forget the sexual dimorphism in the antennae.
♂Anopheles
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27. ♂ CULEX
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28. M. P. OF HOUSE FLY (SPONGING TYPE)
 The head capsule is protruded into a funnel-shaped Rostrum.
The pharynx extends through the rostrum as a narrow pipe.
Dr.ZAbu-Elnaga

29. M.P.OFHOUSEFLY(SPONGINGTYPE)
 Modifications:
 Labium: a thick double walled ( haustellum).
 Labrum-Epipharynx: consists of labrum,
fused with the extended roof of the pre-oral cavity,.
 Hypopharynx: a tongue-like structure resting
along the floor of the haustellum, for receiving the
salivary duct.
 Food-Meatus: a narrow channel enclosed
between the hypopharynx & the labrum-
epipharynx. Extended till the mouth opening
 Labellae: 2 big sponge lobs carried on the tip
of the haustellum, for passage of saliva to dissolve
food before absorption.
 The mandibles: absent
 The maxillae: reduced.
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30. INSECTMORPHOLOGY
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31. THORACIC REGION & ITS APPENDAGES
Thorax
Wings
dorsally
Legs
ventrally
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32. THORACIC REGION
 Carrier to the locomotory organs.
 Each of the three segments carries one pair of jointed leg.
 Dorsally on each of meso- & metathorax it posses one pair
of wings and spiracles.
 Typically structured from 3 sclerotized plates:
 Tergite:( dorsal in position)
 Sternite: (ventral)
 Pleurites: (lateral)
With supporting function from all sides, provide
articulation for wings & legs, protection of the spiracles.
o Between each segments an articulating and bending inter-
segmental membrane, for bending & stretching.
Dr.ZAbu-Elnaga

33. FORMS OF THORACIC SEGMENTS
 Only in primitive insects & immature stages the
thoracic segments similar in shape & equal in
size.
Dr.ZAbu-Elnaga

34. THORACIC APPENDAGE
 The descriptions of the typical structure.
Dr.ZAbu-Elnaga

35. MODIFICATIONS
 The modification in different insects to suit the mode of locomotion or non-
locomotory functions (food collecting).
Running
Cockroach
Jumping
Locust
Walking
upside-down
House fly
Dr.ZAbu-Elnaga

36. Seizing
Fore-leg
Prey mantis
Burrowing
Fore-leg
Gryllotalpa
Swimming
Hind-legs
Water beetles
Dr.ZAbu-Elnaga

37. Food collecting
Hind-leg of Honey bee
worker
Clinging
Lice
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38. INSECTMORPHOLOGY
Dr.ZAbu-Elnaga

39. THE WINGS
 Most adult insects posses 2 pairs of wings (on
meso- & metathorax)
In flies & mosquitoes, the hind pair is reduced
Wings are not modified legs as in birds & bats,
but are additional locomotory organs.
The base of wing articulates with the tergum
& pleuron of the segment carrying it. This
facilitates rotation of the wing during flight in
various directions in relation to the body axis.
Dr.ZAbu-Elnaga

40. TYPICAL STRUCTURE OF THE WINGS
 Triangular, 3 regions (Jugum,
Vannus, & Remigium)
 Wing Axil, posses small sclerotic
(support & articulation)
 In the hind wings of most insects the 3
regions are separated from each other
by 2 folds
 This enables the insect to fold the
hind wings during repose & unfold
them during flight.
Dr.ZAbu-Elnaga

41. HISTOLOGICAL STRUCTURE
 Histologically, a wing is
analogous to a plant leaf,
contains double layer of
flattened cells covered with
extremely thin cuticle
 Enclosing in between the
wing veins (for aeration)&
space for few blood cells
 The wing surface carries
hairs, scales or spicules
Dr.ZAbu-Elnaga

42. WING COUPLING
 For fixing the for-wing with the hind-wing
 This coupling enables the insect to resist the
opposing action while flying at considerable
heights.
1- In honey bee: the costal margin of the hind-wing
posses row of curved hooklets, that anchored to a
chitinous ridge of the anal margin of fore-wing,
(during Nuptial flight)
2- In some moths: the costal margin carries a process
that can fit within a loop extending from the anal
margin.
3- In other moths: the anal margin of the fore wing has
2 clefts enclosing a lobe between them, coupling by
simple overlapping between the lope & the costar
margin of the hind-wing.
Dr.ZAbu-Elnaga

43. WINGCOUPLING
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44. TYPES OF WINGS
 Wings of different insects differ in size, shape, texture & other
structural details.
 Fore-wing usually differ from the hind-wings of the same
insect.
 Function of wings:
1- flight ( rotationary vibrations effected by thoracic muscles).
2- Abdominal protective shield (fore-wing Elytera of beetles).
3- Balancing organs (modified hind-wing halteres in flies &
mosquitoes).
4- Sound-producing organs for calling mates (♂ crickets).
5- Important for insect classification (different types & mode of
development.
Dr.ZAbu-Elnaga

45. TYPESOFWINGS
1- Tegmina (Leathery)
Cockroach
2- Elytra (elytron)
Coleopterous
3-Hemi-elytra
Hemiptera
4- Hairy type
Thrips
5- Lace type
Neuroptera
6-Scaly type
Lepodoptera
7- Membranous type
Hymenoptera
8- Haiteres (Balancers)
Diptera
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46. Dr.ZAbu-Elnaga

47. INSECTMORPHOLOGY
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48. ABDOMINAL REGION & ITS APPENDAGES
 It carries paired spiracles laterally
 The gonophores postero-ventrally & the anus
terminally.
 Contraction of abdominal muscles facilitates
hatching, molting & oviposition.
 In apodous stages it was responsible for
locomotion (vermiform movements).
Dr.ZAbu-Elnaga

49. THE ABDOMINAL SEGMENTS
 Number: variable, the decrease in number is due to fusion, atrophy, or
modification.
 Typical structure: a tergite, a starnite & 2 pleurites
 Types: distinguished into:
1- Visceral S: constitute the major part of the abdomen next to the thorax
(no appendages)
2- Genital S: the subterminal 2 segments carries the gonopore & genitalia
(sexual function)
3- Post-Genital (Anal or Caudal) S: the terminal one or 2 segments carry
Anus & Cerci (similar in both sexes)
Dr.ZAbu-Elnaga

50. MODIFICATIONS
 Structural modifications are common in the genital &
caudal segmants. Examples are:
 Last tergite in most big insects is split into 3 plates (2
lateral paraprocts & a median epiproct) for anus
protection and facilitating egesting
 7th sternite in ♀ cockroach, enlarged & boat shaped to
protect the genitalia & holds the egg capsule
 9th sternum in ♂ cockroach enlarged to protect the
genitalia & carries 2 thin sensory processes (Styli)
 Last sternum in ♀ lice is clefted to facilitate mating &
oviposition
 Terminal 3 segments in ♀ house fly reduced to retractile
telescoped tubules for oviposition
Dr.ZAbu-Elnaga

51. VISCERAL APPENDAGES
• During immature stages some visceral segments carry paired
appendages for locomotion or aquatic breathing. In most of them
they were disappeared before maturity , but in Collembola they
remain
• types:
1- Prolegs: Caterpillars (5 pair of prolegs joined the ventral side
of 3rd, 4th, 5th, 6th, & 10th abdominal segments , they ends with
ring of curved hook-lets for clinging facilitation & climbing.
Additionally, they help the thoracic legs but differ from them in
position and structure (disappeared in the adult stage)
Dr.ZAbu-Elnaga

52.  Tracheal gills: feather-like lateral extensions of the
anterior 7 abdominal segments (May fly nymphs)
Dr.ZAbu-Elnaga

53. SPRINGING APPARATUS
Springing apparatus: found in Collmbola, consists of
1- Colliphore (=Adhesor for adhesion)
2-Hamula (Clasper), hold the furcula during repose
3-Furcula (Spring) a long biforked flexible process extending from the latst (5th)
segment.
Springing takes place as follows
a. The fluid is withdrawn from the vesicles of colliphore, then collapse & the
insect gets free from substratum
b. The furcula is released from the clasper to return backwards in a sudden
movement (so, insects springs forwards swiftly)
Dr.ZAbu-Elnaga

54. INSECTMORPHOLOGY
Dr.ZAbu-Elnaga

55. ANAL (CAUDAL) APPENDAGES
1- Cerci:
One pair carried by the last segment in both sexes
With different shape & size in different insects
All of them are tactile in function
Caudal gill plates, the terminal segment carries 3 leaf-like
thin walled gill plates for aquatic breathing (Damselfly
nymphs)
Dr.ZAbu-Elnaga

56. TYPES OF CERCI
 Short unsegmented (Locust)
 Short, spindle shaped & segmented (cockroach)
 Long segmented & setaceous (silverfish)
 Forceps-shaped with serrated inner edges (ear-wigs) (for defence & preying)
Dr.ZAbu-Elnaga

57. GENITAL APPENDAGES (GENITALIA)
♂ GENITALIA
 Penis: median hollow organ, joining the 9th sternum basally &
carrying the ♂ gonopore (copulatory)
 claspers: one pair in some insects, enclosing the penis in-between
 styli: in cockroaches only, one pair of thin unsegmented process
Dr.ZAbu-Elnaga

58. ♀ GENITALIA (OVIPOSITOR)
 8th & 9th segments modified to an egg-laying
apparatus (by governing the egg deposition)
 Honey bee, cockroach, grasshopper & parasitic
wasps
 Typical structure: 3 pairs of valves, enclosing the
gonopore
 Forms of ovipositors: depending on differ in shape &
size of valves, for different oviposition habits & other 2ry
functions
 Function: 1- digging tunnels (Locust)
 2- tearing plant leaves (Thrips)
3- piercing & narcotizing (parasitic wasps)
4- defense & attack (honey bees)
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59. FORMS OF OVIPOSITORS
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60. STINGOFHONEYBEE
Modified ovipositor
In worker only for defense or attack
Structure:
Dr.ZAbu-Elnaga

61. Please consider the following in your comments about the course.
Would you prefer weekly quizzes rather than the “practice
quizzes?
Are the listed objectives helpful?
Are the study materials helpful?
Is the list of terms helpful? The glossary?
Are the video clips helpful or distracting?
What can I do to improve attendance?
Would you recommend the course to a friend? An enemy?
Did the course meet your needs now and in future?
Were the exams representative of material presented in the
course?
Would you prefer to have a detailed text book if available at
reasonable cost?
Please, list any suggestions for improving the course?
please, state your accepted skills during studying this course?
COURSE EVALUATION
Dr.ZAbu-Elnaga

62. CITATION & REFERENCES
1- Text book of “Fundamentals of applied entomology”. 3rd
edition, by Robert E. Pfadt. Macmillan publishing Co.,
INC. New York, 1971.
2- note book of “Entomology” 2nd year biology, published by
the Zoology Dep., Faculty of Science Mansoura University.
http://images.google.com/images?hl=en&um=1&q=Forms+of+
ovipositors+of+insects&sa=N&start=100&ndsp=20
http://en.wikipedia.org/wiki/Insect
http://www.earthlife.net/insects/anatomy.html
http://www.amazon.com/Principles-Insect-Morphology-
Comstock-Book/dp/0801481252#reader
http://www.youtube.com/watch?v=Jpcpn5NX62c (honey bee
feeding)
http://www.youtube.com/watch?v=L1bi-8uRCaU (house fly )
http://www.youtube.com/watch?v=7V_GBQclQfc (mosquito)
http://www.youtube.com/watch?v=daYvNM2IuOg (cockroach)
Recommended Text: The Insects, Structure and Function, by
Chapman.
Recommended Text: Evolution of the Insects, by Grimaldi
and Engel.
Recommended Text: Principles of Insect Morphology, by
Snodgrass
Dr.ZAbu-Elnaga