Insect head and antenna

1. Structure and Modifications of
Insect head and antenna
Prepared by
Dr. S. Sumaiya

3. Structure of insect head
 Head capsule is sclerotized and the head capsule excluding
the appendages formed by the fusion of several sclerites is
known as Cranium
Sclerites of Head
 Vertex
 Frons
 Clypeus
 Gena
 occiput
The surface of the head is divided into regions (sclerites) by a pattern of
shallow grooves (sutures).

4. Sutures of head
 Epicranial
 Epistomal/ fronto
clypeal
 Clypeo labral
 Post occipital

5.  Posterior opening of the
cranium through which aorta,
foregut, ventral nerve cord and
neck muscles passes is known
as Occipital foramen.
 Endoskeleton of insect cuticle
provides space for muscle
attachment of muscles of
antenna and mouthparts –
Tentorium.
 Cephalic appendages :
antenna, eyes, mouthparts
Structure of insect head

6. Insect Heads
3 basic types
Hypognathous
Prognathous
Opisthorhynchous

7. Hypognathous head
(Hypo = below; gnathous = jaw)
 This type is called orthopteroid type. The long axis of the
head is vertical. It is at right angles to the long axis of
the body. Mouth parts hang ventrally downwards from
head capsule.
 eg. Grasshopper, cricket, molecricket, cockroach,
preying mantis, caterpillars, and most phytophagous
insects living in open habitats.

8. Prognathous head
(Pro = infront; gnathous = jaw)
 This type is also called coleopteroid type. The long axis
of the head is horizontal. It is in line with the long axis of
the body. Mouth parts are directed forward.
 eg. Ground beetle, soldier termite, and predators that
actively hunt their prey (grub and adults of beetles and
the grub of green lacewings).

9. Opisthognathous head (Opistho =
behind; gnathous = jaw)
 This is also called hemipteroid type or opisthorhynchous
type.
 Head is deflexed.
 Mouthparts are directed obliquely backwards (ventro-
posteriorly) and held in between the forelegs.
 eg. Stink bug.

10. Types of Insect Antennae

11. Antenna
 One Pair on head
 Jointed
 Sensory (smell)
 Called “feelers”
 Filiform most common
shape (segments = size)
 May be modified
FILIFORM

12. Antennal
suture
Antennifer
Pedicel
Scape
Flagellum
Antennal
socket
Antennal
sclerite
Insect Antenna

13. Segments in antenna
1. Scape: The basal segment is called scape. It is conspicuously
larger than succeeding segments. It is provided with intrinsic
muscles.
2. Pedicel: The second antennal segment is called pedicel. A mass
of sense cells called Johnston's organ is present in the pedicel,
which is used as a ‘chordotonal organ’ (chord + tonal) in some of
the insects like mosquitoes. Pedicel is also provided with intrinsic
muscles.
3. Flagellum: The remaining annuli or flagellomeres are known as
flagellum (plural - flagella) or clavola. Flagellomeres are not true
segments because they lack intrinsic muscle. Surface of the
flagellum is supplied with many sensory receptors that are

14. Setaceous antenna
 These are simplest type of antenna having
bristle shape
 They are found in dragon fly

15. Capitate antenna
 Abruptly clubbed at the end.
 Example-butterfly

16. Clavate antenna
Eg: Blister beetle

17. Filliform antenna
 They have thread like shape
 Example-ground beetles

18. Geniculate antenna

19. Moniliform antenna

20. Pectinate antenna (Unipectinate – comb
like)

21. Bipectinate (Double comb like)

22. Serrate antenna
 They are saw toothed shape
 Example-click beetles or longicorn beetles

23. Aristate Antenna

24. Plumose antenna
 Segements with long whorl of hairs
 Ex: Male mosquito

25. Pilose (Hairy)
 Antenna is less feathery with fewer hairs at the
junction of flagellomere
 e.g. female Culex mosquito.

26. Lamellate (Plate-like)
Antennal tip is expanded laterally on one side to form
that plates

27. Flabellate (Fan like)
very small, third and subsequent segments
with side processes giving fan like
arrangements.
Ex: Cedar beetle, Strepsipterans

28. Stylate antenna
Terminal segment bear
a style like process
(Flagellum forms a
long un segmented
terminal hair
Ex: Horse fly