The insect head is composed of sclerites including the vertex, frons, clypeus, gena, and occiput. It is divided by sutures and contains openings like the occipital foramen. The head supports appendages like the antennae and mouthparts. There are three basic head types - hypognathous, prognathous, and opisthognathous - which differ in the orientation of the mouthparts. Antennae are jointed sensory organs that can be filiform or modified into various shapes like capitate, clavate, geniculate, and pectinate. They are composed of segments including the scape, pedicel, and flagello
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
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.
11. Antenna
One Pair on head
Jointed
Sensory (smell)
Called “feelers”
Filiform most common
shape (segments = size)
May be modified
FILIFORM
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