fundamental entomology

1. FUNDAMENTAL OF
ENTOMOLOGY

2. Ex:1 Observation on external features
of grasshopper/ cockroach
Insect body segments:
Generally insect body segments are grouped into 3
regions called tagmata . The grouping of
segments into function units of body is called
tagmosis.
1. HEAD
2.THORAX
3.ABDOMEN

4. HEAD
• First anterior tagma
• Head is Heavy sclerotized
• Hardened head capsule called cranium
• Head capsule is covered with hardened plates or sclerites
• Soft parts of joints between sclerites are called sutures
APPENDAGES OF INSECT HEAD :
1. compouns eye
2. Simple eye
3. Antenna
4. Mouth parts

5. Compound eye- dorosolateral
• Individual sendory units called ommatidia
• They are photoreceptors, receive mosaic
image and able to differentiate colour.
Simple eye- anterior portion of the carnium
between compound eyes
• Have single lens
• They are sensitive to light but not useful in
image perception

6. Sclerites of head:
• Vertex- summit of the head between compound eyes.
• Frons- Facial arear below the vertex and above clypeus
• Clypeus- cranial area below the forns to which labrum
attached.
• Gena- lateral carnial area behind the compound eyes
• Occiput- carnial area between occipital andpost
occipitial sutures.

7. • Sutures of head – linear invaginations of the
exoskeleton between two sclerites are called suture
(sulcus)
• Epicranial suture/ ecdysial line: inverted ‘Y’ shaped
suture,
• Epistomal suture/ fronto clypeal suture: between frons
and clypes.
• Clypeo-labral suture: between clypeus and labrum
• Postoccipital suture: bordering occipiyal foramen.line
indicating the fusion od maxillaryband labial segment.

8. ANTENNA
• Paired segmented appendages that articulate with
cranium between the compound eyes.
• Antenna are flexible and sensory in function.
MOUTHPARTS
Organ of feeding.
Upper lip( labrum), lower lip(labium), a pair of primary
jaw(mandibles), a pair of secondary jaws(maxilla)
and a tongue like structure hypopharynx.

9. THORAX:
• Middle region, highly musculated and locomotory centre
• Three segment : Prothorax
Mesothorax
Metathorax
Name of regions: Notum/tergum (back)- tergite
pleuron(side)- pleurite
Sternum(chest)- sternite.
The notum of prothorax, mesothorax, metathoraxis called as
pronotum, mesonotum, metanotum.
Pronotum of grasshopper is saddle shaped.

10. Appendages: Two pairs of wing
Three pairs of legs
• Wings: wing bearing segments are mesothorax
and metathorax collectively called as pterothorax
(ptera-wings) 1st pair (fore wings) in mesothorax
2nd pair (hind wings) in metathorax.
• Legs: three pairs of legs. Each thoracic segment
bears a pair of legs
• Fore leg- prothorax
• Middle leg- mesothorax
• Hind leg- metathorax.

11. ABDOMEN: It is a thrid functional region( posterior
tagma), longest region,
• Posterior abdominal segements are modified for the
purpose of mating (copulation) and oviposition (egg
laying)
• 11 telescopic segments, each segement arched
dorsal sclerite and ventral plate sclerite.
• No pleuron, tergum is connectes to sternum by thin
membrane called ‘ conjunctiva’.
• Abdomen is soft compared to rest of the body.

12. Organs/ structures in abdomen:
Tympanum: it is a hearing organ. Oval shaped auditory
membrane( ear drum) in lateral side of the 1st abdomen
segment.
Spiracles: eight pair of abdominal spiracles on lateral side of first
eight abdominal segments.
Anus: At the end of abdomen, situated between epiproct and
paraprocts located in 11th segment of abdomen.

13. • Cerci: a pair of short unsegmented cerci is located in
between the epiproct and paraprocts. They are
sensory in function.
• Genetalia: the insect genetalia lies below the anus.
• In male genitalia are located in 9th segement, it
consists of median intromittent organ called
aedeagus and styli present only in male

14. • In female 8th and 9th segments are fit together to form an egg
laying apparatus called ovipositor, used to dig the soil during
oviposition.
• Consists of 3 pair of valvifers, one valvifer in 8th segment and
two pair of valvifers in 9th segment.

15. EX NO:2 METHODS OF INSECT
COLLECTION, PRESERVATION, DISPLAY
AND STORAGE
Insect collecting equipments:
• Insect net
• Aspirator
• Berlese funnel
• Baiting
• Traps
• Hand picking

16. INSECT NET:
Three types of insect net
Aerial net, sweep net, aquatic net/dip net
Aerial net (butterfly net)- used to collect aerial insects during
flight Eg; butterflies, moth, dragonflies, wasps.
Light in weight.
3 parts- metal ring hoop (30-45cm dia) long wooden/ aluminium
handle(90-120 cm)
Porous cloth/mosquito net cloth bag.

17. • Sweep net- heavier than aerial net
• Used to collect leaf hopper, grasshoppers, small insects
• Large hoop(38cm dia), shoprt stout handle (75cm long) and
muslin cloth bag/ tough cotton cloth bag.
• Aquatic / Dip net- used to collect aquatic insects from running
water.
• It is similar to aerial net, except length of the bag

18. Aspirsator: also called as “pooter”.
Used to collect small and minute insects without and damage
Berlese funnel: to collect soil inhabiting insects
like mites, collembolans from debris, organic
matter, litters in soil.

19. • Baiting: insects attracting baits viz., sugar, rotting fruit, meat,
animal dung are used to collect the domestic insects
(cockroach, flies, ants, beetles, termites).
• Traps: types traps for collecting various insects. Light
trap(phototropic insects), sticky trap( flies), water pan
trap(planthopper), pitfall trap( ants, antlion grubs and other
soil insects).

20. • Hand piciking: large and less active insects can be collected.
Stinging and biting insects can not be collected eg., beetles,
grasshoppers etc.
• PRESERVATION OF INSECTS:
• Paper envelops or triangels or folds- large winged
insect like drangofly, butterflies can be temporarily
preserved after collection (to preseve wing
colouration).
• Cut the absorbent paper or newspaper into
rectangles with sides of 3:5
• Bring the diagonally opposite corners together to
leave two projecting flaps.
• Keep the immobilised insects in between overlappin
trinangles.

21. • Relaxing container: stiffness in the dead insect can be
removed by placing it in relaxing container.
• Jar in made of restless metal, tin, glass with tightly fitting lid
• Contain a layer of sand(5 cm), any absorbent material
(synthetic sponge), which satured with water and few drops
of formalin or carbolic acid.
• Keep dried specimens in the jar allow a day or untill they
become flexible.
Entomological pins
Setting board: useful for spreading the wings of
insects

22. METHODS OF PRESERVATION:
Dry preservation- it is the best and common method to preserve
hard bodied insects can be pinned directly.
Place of insertion of the pin varies among different groups of
insects
Name of the insect Place of insertion of pin
Most insects thorax
Drangonflies and damselflies Center of thorax
Earwig Right tegmen
Grasshopper, crickets, preying
matids and cockroach
Mid line of the pronotum
Stick insect Metanotum
Bugs Right side of scutellum
Beetles Right elytron
Flies, wasps and bees Mesothorax
Butterfly and moth Centre of the prothorax

24. Double mounting: when insect are too small it is done
Staging- medium sized insects pinned by minuten pinto
the stage made of cork or pith.
Carding- speciment is stuck on to a trianglar/ rectanglar
white card.

25. • Liquid preservation: soft bodied insects like
sliverflish, springtails, mayflies, aphids,
thrips,immature stages viz., caterpillar, grubs etccan
be directly preserved in liquids like 70% ethyl alcohol
or methylated spirit and formalin (4%).
• Setting /strecting/spreading: it essential for display
of their features and to study the characters.
• Setting boards are used for setting, before insect
become stiff.
• Labelling: label should be of uniform size ,cut out
from the stiff paper or card. Label should contain
name of the locality, date of collection and name of
collector, insect, host, and systematic details of
insects.

26. DISPLAY AND STORAGE:
Storage box: box are made of wood should be lightweight, air
tight and moisture proof with a well fitting lid.
Glass topped boxes are used for displaying collections.
Ricker mounts: it is a flat container having glass or transparent
cover. Used for mounting specimen or life cycle of insect
specimen.

27. THANK YOU

28. EX NO. 3: TYPES OF INSECT HEAD AND
ANTENNAE
Insect head: Fusion of six segment
Types of insect head:
• Hypoganathous head (hypo- below/ gnathous- jaw)
• Prognathous head (pro- infornt/ gnathous- jaw
• Opisthognathous head (opistho- behind/ gnathous-
jaw)

29. • Hypognathous head: orthopteroid type, long axis of
head is vertical .
• It is ringle angle to the long axis of the body.
• Mouth parts hang vertrally downwards from head
capsule. Eg. Grasshopper, cricket, cockroach, preying
mantis, caterpillar.

30. • Prognathous head: it is coleopteroid type.
• The long axis of the head is horizontal.
• Mouth parts are directed forward. eg,. Ground
beetle, soldier termite, grubs and adult of
beetles and grub of lacewing.

31. • Opisthognathous head: it is hemipteroid type
• head is deflexed. Mouth parts are directed obliquely
backward and held in between the forelegs. eg. Stink
bug.

32. Types of antenna:
• Antenna are also called as feelers. They paired, highly
mobile and segmented.
• Antennae are well developed in adults and poorly
developed in immature stages.
• Antenna is set in a socket of the cranium called
‘antennal socket’.
• The base of the antenna is connected to the edge of
the socket by an ‘articulatory membrane’. This
permits free movement of antenna.

33. Segment in antenna:
Scape- The basal segment is
scape. Large than succeeding
segments. It is provide with
intrinsic muscles.
Pedicel- A mass of sense cells
called “Johnston’s organ”. Used
as a chordotonal organ.
Flagellum- The remaining
flagellomeres are known as
flagellum or clavola.
Surface of the flagellum is
supplied with many sensory
receptors that are innervated
by the deutocerebrum of brain.

34. Function of antenna:
• Organ of smell and touch( to detect chemicals- food
pheromone).
• Perceive forward environment, detect danger,
variation in temperature, vibration, humidity, wind
velocity and direction.
• For sexual dimorphism( mosquito)
• Useful for hearing(mosquito) and communication
(ants).
• Rarely, useful to clasp the mate (eg. Flea) and grap
the prey.

35. • Types of antenna: Flagellum may
vary in size and form, which makes
antenna to be of different types.
• Setaceous (seta-bristle) –
reduction in size of the segments
from base to tip
• Flagellum has few segments.eg.
Leafhopper, drangonfly and
damselfly.
• Filiform (filum-thread) – number of
flagellomeres is more than the
setaceous type.
• Segments are cylindrical and
uniform in thickness

36. • Moniliform (monile- necklace)-
segments are either globular or
spherical in shape and uniform in
size.
• Look like a string of beads.eg.
Termite
• Serrate(serra –saw)- segments in
the distal two third of the flagellum
are notched or angled one side.
• Short tirangular projection on one
side. it make a look like saw blade.
SERRATE

37. • Unipectinate (pectin –comb)-
flagellomers extend into long
slender lateral processes from
middle of segment on one side
which gives comb- like
appearance. Eg. Sawfly
• Bipectinate (double)- eg.
Silkworm flagellomeres extend
into long slender lateral
processes from middle of the
segment on both side
• Double comb like appearence

38. • Clavate (club/knot)- flagellomeres
enlarges gradually towards the tip,
giving knot like appearance at tip .
• eg. Blister beetle, lady bird beetle.
• Capitate(caput-head like)-
proximal flagellomeres are slender
and uniform size , distal terminal
segments enlarged suddenly
modified into capitullum.
• Eg. Butterfly, owlfly.

39. • Lamellate (thin or small plate )-
terminal three flagllomeres
expand laterally on one side to
form flat plates.
• Eg. Dung roller, rhinocerous
beetle.
• Aristate (arista-fine bristle)-
flagellum in undivided swollen
segment, bear a conspicuous
dorsal bristle called arista.
• Eg. housefly

40. • Stylate (style like)- terminal
flagellomers bear a style like process.
• Eg. Horsefly, robber fly.
• Plumose (feathery)- junction of
flagellomers bears long whorls of
hairs, looks like feather. Eg. Male
mosquito.
• Pilose (hairy)- junction of flagellomers
bears short and fewer hairs look like
less feathery.
• Eg. Female mosquito.

41. • Geniculate (small knee, Elbowed)- scape is
long remaining segments are small and are
arranged at an angle to the first
resembling an elbow joint.
• Eg. Ant, Weevil, honey bees.
• Flabellate (fan like) – flagellum with flat
thin process on each side like the fold of a
fan. Eg. Cedar wood beetle.
• Fusiform (spindle shaped)- flagellum
broader in the middle and tapering at both
ends.
• Eg. Sphingids.