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Cockroach: Morphology and Anatomy of Cockroach

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Cockroaches belong to the order Blattodea, the family of Blattidae and the Genus Periplaneta. There are around 4000 different species of cockroach around the world. However, only a few of them can be found in the Indian subcontinent. 

Some of the common species include – German cockroach (Blatella Germanica), American cockroach (Periplaneta Americana), oriental cockroach (Blatta Orientalis) and the brown-banded cockroach (Supari Longipalpa). To know more about the different species of cockroach and their scientific names, refer to our morphology and anatomy of cockroach notes.


  • Brown/black body, bright yellow, red & green in tropical.
  • Size 1/4th inch to 3 inches (0.6 -7.6 cm), long antennae, legs, the flat extension of upper body conceals Head, serious pests, reside in human homes.
  • Nocturnal omnivores, damp place throughout the world.

 Morphology of Cockroach

  • Segmented, divisible to head, thorax, abdomen.
  • The chitinous exoskeleton, hardened plates – Sclerites (tergite dorsally & sternite ventrally), joined by thin & flexible articular membrane.
  • Adults – Peri planta Americana (34 – 53 mm), wings extended beyond the tip of the abdomen in males.


Morphology of Cockroach


  • Head – triangular, anteriorly at 900 to the body axis, a fusion of 6 segments, mobility in all direction (flexible neck), bears compound eye. Thread is antennae from sockets in front of the eye.
  • Antennae – Sensory receptor, monitor Environment.
  • Anterior mouth – Biting & chewing.
  • Mouth – Labrum (upper lips, pair of mandibles, pair of maxillae, labium (lower lip)
  • Median flexible lobe acting as the tongue (Hypopharynx) within the cavity by mouth.
  • Thorax – Prothorax, mesothorax, metathorax.
  • The Head is connected to the thorax by the neck (short extension of prothorax). Each thoracic segment – pair of legs.
  • First pair of wings – mesothorax, Second pair – metathorax
  • Forewings (mesothoraces) – tegmina are dark, opaque, bather, cover hind wings at rest.
  • Hind wings – Transparent, membranous, flight.
  • Abdomen in male and female – 10 segments (jointed filamentous structure- anal cerci)
  • In female – 7th sternum (boot shape) and with 8th & 9th form brood/genital pouch where anterior has gonopore, spermathecal pore, collateral glands.
  • In a male, genital pouch (hind end of the abdomen) dorsally by 9th & 10th terga, ventrally by 9th sternum, has a dorsal anus, ventral genital pore & gonapophysis, bear short, thread-like anal styles (-in females)


Anatomy of Cockroach

1 .Digestive System of Cockroach

  • Foregut + midgut + hindgut
  • The mouth opens to the tubular pharynx to the esophagus (tubular passage), opens to sac-like structure – crop (store food), followed by gizzard/ proventriculus.
  • Outer thick circular muscle, inner cuticles are forming six chitinous plate – teeth.
  • Gizzard in grinding food. The foregut is lined by the cuticle. 6-8 blind tubules – hepatic/gastric Calca at the junction of fore & midgut, secrete digestive juice.
  • At the junction of mid & hindgut – ring of 100-150 yellow color thin filamentous Malpighian tubules (remove products from hemolymph)
  • Hind gut is broader (ileum + colon + rectum) than mid-gut.
  • The rectum opens through the anus.

Click Here for Complete Biology Notes

Digestive System of Cockroach

2. Vascular system of Cockroach

  • Open types, poorly developed vessels, open to hemocoel.
  • Visceral organs in the hemocoel are bathed in the hemolymph.
  • Hemolymph – colorless plasma + hemocytes.
  • Heart – Elongated tube along the mid-dorsal line of thorax & abdomen, differentiated to a funnel-shaped chamber with Ostia on either side. Blood from the sinus enters through Ostia, pumped anteriorly to sinuses again.

Vascular system of Cockroach

3. Respiratory System of Cockroach

  • Network of the trachea, open through 10 pairs of small holes – Spiracles (lateral side), opening by sphincters.
  • Branching tubes (tactual tubes -tracheoles) carry O2 from air to all parts.
  • Exchange of gases at tracheoles by diffusion.

4. Excretion system of Cockroach

  • Malpighian tubules (glandular & ciliated cell)
  • Absorbs nitrogenous waste – uric acid – excreted by hindgut.
  • Uricotelic, fat body, nephrocyte, reverse glands also help in excretion.

5. Nervous system of Cockroach

  • Fused, segmentally arranged ganglia, joined by C.T. on ventral.
  • Three ganglia in the thorax, 6 in the abdomen; spread throughout.
  • Head holds bit nervous system, rest along the ventral side.
  • If the Head is cut off, it will live for one week.
  • Brain by supraesophageal ganglion (nerve to antennae & compound eyes).
  • Sense organs – antennae, eyes, maxillary palps, labial palps, anal cerci.
  • Compound eye – Dorsal side, 2000 hexagonal ommatidia (receive several images) – mosaic vision (increase sensitivity decrease resolution), common at night (nocturnal).

6. Reproductive system of Cockroach

  • Dioecious, well developed.
  • Male – pair of testes on the lateral side of 4th – 6th abdominal segment, from them vas deferens arise opening to ejaculatory duct through seminal vesicle, then to male gonopore on the ventral side to the anus.
  • Mushroom shape gland (6th – 7th) accessory gland.
  • External genitalia – Male gonapophysis/phylloxera (chitinous asymmetrical structure).
  • Sperms in the seminal vesicle, glued to form spermatophore.
  • Female – Two large ovaries, laterally in 2nd -6th segment.
  • Each ovary – group of 8 ovarian tubule(ovarioles) containing chain of developing ova.
  • Oviducts unite to a single median oviduct, opens to the genital chamber. Pair of spermatheca (6th) opens to the genital chamber. Fertilized eggs are enclosed in capsule – Oothecal (Dark reddish to blackish capsule),3/8 inch (8mm) long.
  • Dropped to suitable surface (crack of high humidity near food sources).
  • Female produce 9-10 oothecal (14-16 eggs), pest spoil food (smelly excreta), diseases.
  • Many are wild, no economic importance, thrive in or around human habitat. 
  • P. americana – paurometabolous (div. by nymphal stage), nymph looks like adult, grows by molting about 13 times to reach adult form.
  • Next to last nymphal stage has wing pads; only adults have wings.

Reproductive system of Cockroach



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