Cockroach Morphology Short Notes | Free Biology Notes

Cockroach Morphology Short Notes

In this article we will discuss about the cockroach morphology

Cockroach Morphology

  • Cockroaches are brown or black bodied animals
  • Inhabiting the unhygienic and damp places
  • Cockroaches are nocturnal, omnivorous, cursorial and exhibit cannibalism
  • Cockroach can run 130 cm/sec
  • They also transmit various types of bacterial diseases
  • Adults cockroach are about 34-53 mm long with wings
  • Body divided into head, thorax and abdomen
  • Body divisible into segments and some segment fuses in adult stage
  • Body is covered by hard chitinous exoskeleton
  • Exoskeleton of chitin plates occurred in each segment
  • Chitin plate called sclerites
  • Sclerites joined each other by membrane called arthroidal membrane
    • Sclerites of dorsal side – tergum or tergite
    • Sclerites of lateral side – pleura or pleurites
    • Sclerites of ventral side – sternum or sternite


  • Head is triangular and hypognathous
  • Head is formed by fusion of six segments
  • Sclerites of the head joined fully and form head capsule
  • The head bears a pair of compound eye, a pair of antennae.
  • Each compound eye made up of 2000 units called ommatidia
  • Antennae have sensory receptors
  • Head bears appendages meant for biting and chewing types of mouth parts
  • Mouth situated in the anterior side of head which is surrounded by mouth parts

Mouth Parts Of Cockroach

A labrum (upper lip)

  • Broad and roughly rectangular shaped structure
  • Bear chemoreceptor on inner side

A pair of mandibles

  • Pair of hard, strong, large, dark coloured structures found one on either side
  • They bear pointed teeth like structure and crush the food present in between them

A pair of maxillae

  • Lie outside and behind the mandibles & made up of five segment
  • Function: cockroach pickup its food and put it in preoral cavity for chewing.
  • Maxillary palps also used as brush to clean antenna and wing.

A labium (lower lip)

  • Labium is formed by the fusion of the second pair of maxillae
  • It forms the broad median lower lip and has a pair of 3-segmented labial palps on either side which is bear taste receptors


  • A median flexible lobe acting as tongue
  • It bears several sensory setae


  • Thorax is the middle part of the body
  • Thorax consists of three segments – prothorax, mesothorax and metathorax.
  • Each thoracic segment bears a pair of walking legs
  • Thorax has two pairs of wings on the dorsolateral side.
  • Each leg is made by 5 segments
    • 1st podomere is coxa: broad and attached to the thorax. It is the most swollen segment
    • 2nd podomere is trochanter: It gives viability for movement of leg
    • 3rd podomere is femur: strongest part of the leg. It shows bristles.
    • 4th podomere is tibia: longest part of the leg. It also bears bristles
    • 5th podomere is tarsus: tarsus made up of five segments called tarsomeres and the last one is called pretarsus
  • Each pretarsus bears one pair of claws and large adhesive pads arolium or pulvilus.
  • Cockroach move on the smooth surface by the help of arolium and on rough surface with the help of claws
  • Tactile setae are present on each segment of legs.

Two pairs of wings present

Fore wings (tegmina or elytra)

  • First pair of wings arises from mesothorax
  • Long, narrow, leathery strong
  • Its cover full abdomen and cover the hind wings when at rest
  • In male fore wings projecting out ward from abdomen

Hind wings

  • Hind wings arises from metathorax
  • Small, broad, thin and soft
  • These wings help in flight
  • They are folded like a fan and covered by elytra while at rest.


  • Abdomen is broader than thorax and consists of 10 segments while embryo has 11 segments.
  • All characters of sexual dimorphism in cockroach present in abdomen
  • 10th segment in both sexes bears a pair of small, filamentous and sensory anal cerci
  • Each anal cercus is made of 15 segments.
  • In male, in addition of anal cerci, 9th sternum bears anal style (unjointed thread like) which are absent in females
  • Sternum: In male 9 sternum & In female 7 sternum present
  • In female 7th,8th,9th sterna form a brood or genital pouch

Frequently Asked Questions: –

It's a type of head orientation. Hypognathous, meaning that the head is orientated vertically. Mouth parts are pointed down.

The head bears a pair of compound eye, a pair of antennae. Each compound eye made up of 2000 units called ommatidia. Many ommatidia work together to give vision.

In male, in addition of anal cerci, 9th sternum bears anal style (unjointed thread like) which are absent in females.

You may also like: –

For more detailed information about Structural Organisation in Animals, download now full study material as PDF and if you want to learn more detailed information about Structural Organisation in Animals, visit YouTube Channel.

Leave a Comment