Updated: Oct 27, 2021
Genus- Periplanetta, Blatta
Species- More than 4500 species of cockroaches
Habitat- Warm, dark and damp places like kitchen, store houses, sewers.
Body size- Length- 0.6cm - 7.6cm; Periplanetta americana- 3.4cm- 5.3cm.
Body shape- Dorsoventrally flat.
Body color- Usually Brown or black; some species have yellow, red, green body color.
Body symmetry- Bilateral symmetry.
Habit- Nocturnal i.e. feeds at night time.
Exoskeleton- Made up of hard chitinous plates called Sclerites.
Nutrition- Omnivores/ Scavengers/ some species of cockroaches show Cannibalism.
Most common species of cockroaches are Periplanetta americana (American cockroach) and Blatta orientalis.
Cockroaches are considered as serious pests and are vector for several diseases.
Body is divided into 3 distinct regions- Head, Thorax and Abdomen.
Triangular in shape.
Made up of 6 chitinous plates called Cephalic sclerites in Embryo.
In adults, the cephalic sclerites are fused to form a single Head Capsule.
I Cephalic sclerite- Occiput- present at the top of head and is made up of 2 parts called Epi-cranial plates joined at Epi-cranial suture.
II Cephalic sclerite- Frons- present below the occiput on anterior part of the head.
III Cephalic sclerite- Clypeus- present just below the Frons on the anterior part.
IV Cephalic sclerite- Post-Occiput- present downward to the posterior part of Occiput.
V Cephalic sclerite- Gena- present on the lateral position.
VI Cephalic sclerite- Post-Gena- present inner to Gena.
Head also has mouth parts and several sense organs on it.
Mouth is downward facing called Hypognathous mouth.
Mouth type is bitting and chewing type.
Made up of several parts- Labrum, Mandibles, Maxilla, Hypopharynx, Labium.
Labrum- also known as upper lip which hangs from Clypeus.
Mandible- a pair of Mandibles are present inner to Labrum and consists of grinding and incising regions for cutting the food.
Maxilla- a pair of Maxilla are present beneath the Mandible for mastication of food, helps in cleaning the antennae and also has Maxillary palp consisting of olfactory receptors.
Labium- also known as lower lip and is formed by fusion of two parts. A pair of Labial palp also arises from Labium which consist of sensory bristles attached to it.
1.2 sense organs
Multi-segmented and each segment is called Podomere.
Long and filiform.
Arises from Antennal sockets.
Bears tactile, thermal and olfactory receptors to monitor the surroundings.
1.2.2 COMPOUND EYES
Dorsolaterally placed on top of the head
Made up of 2000 units called Ommatidia.
Produces mosaic vision
1.2.3 OCELLUS/ FENESTRAE
Present inner and upper to each antennal sockets.
Vestigeal simple eyes.
Divided into 3 segments:-
Each segment of thorax is made up of 4 chitinous sclerites called dorsal Tergum, 2 lateral Pleura and ventral Sternum.
The Tergum of Prothorax called Protonum is extended to protect the neck and is the largest sclerite.
Each thoracic segment bears a pair of legs called Pro-legs, Meso-legs and Meta-legs arising from Prothorax, Mesothorax and Metathorax respectively.
2 pair of wings called Forewings and Hindwings arises from Mesothorax and Metathorax respectively.
Forewings/ Mesothoracic wings- Thick, leathery, and dark in color. Not used for flight but protects and covers the Hindwings.
Hindwings/ Metathoracic wings- Thin, transparent, delicate and broad. Used for flight.
Made up of 11 segments in embryo but reduced to 10 segments in adults.
Abdomen in broader than thorax and dorsoventrally flat.
A typical abdominal segment consist of dorsal Tergum, 2 lateral Pleura and ventral Sternum but the 10th segment lacks sternum.
In males, the 7th tergum covers the 8th tergum but all 9 sternum are visible in males.
In females, the 7th tergum covers the 8th and 9th tergum and the 7th sternum covers the 8th and 9th sternum.
Anal cercus- Long thick structures arising from 10th tergum which bears tactile and phonoreceptors. Present in both males and females.
Anal styles- Thin and small outgrowth arising from 9th sternum and bears tactile receptors. Anal styles are exclusive to males and are absent in females.