Phylum : Arthoropoda

Class : Insecta

Subclass : Pterygota

Order : Dictyogota

Family : Blattidae

Genus : periplaneta

Species : Americana

• Cockroaches are brown-black bodied animals.
• Size : ¼  inch to 3 inch ( 0.6-7.6 cm ).
• They are nocturnal omnivores that live in damp places.
• As cockroach are common in human home, so they are serious parts and act as vector of diseases.

Morphology :-

• Common species of cockroach, Periplaneta  Americana are about 34-53 mm long with wings, that extend tip of the males abdomen.
• Body of cockroach had segments and divided into 3 regions :-

Head, thorax and abdomen.

• The brown colour hard chitinous exoskeleton cover the entire body.
• exoskeleton has hardened plates in each segment called sclerites. That are joined to each other  by thin and flexible artucular membrane known as arthrodial membrane.

Head :- triangular in shape.

• Six segments are fused together to form head  which shows mobility in all directions due to flexible neck.
• A pair of compound eyes are present on head capsule.
• In front of eyes, antennae arises from membranous sockets.
• Monitoring of emrioment is done by sensory receptors present on antennal.
• On the anterior end of the head, mouth parts for biting and cheering are present.
• A Labrum (upper lip) a pair of mandibles, a pair of maxillae and lobium ( lover lip) are the mouth part of cockroach.
• Hypo pharynx is a pair of labe.

Thorax :-

It consist of 3 parts :-

1. Pro thorax .
2. Miso thorax.
3. Mita thorax.

• Nick connects the head with thorax by short extension of pro thorax.
• A pair of walking legs, are present on each thoracic segment.
• There are 2 types of wings present :-

                                      

Fouwings	Hind wings
Arises from mesothorax. Also known as tegima . They are opaque, dark and leathery. They covers the hind wings when at rest.	Arises from metathorax. They are used in flight. They are transparent and membranous in structure.

 

Abdomen:- 

Abdomen of cockroach is divided into 10 segments.

• In males genital pouch lies at the hind end of abdomen bounded dorsally by 9^th and 10^th terga and ventrally by 9^th sternum. Gonapophysic, dorsal anus and male genital pou are present here.
• In females, 7^th sternum is boat shaped.

Genital pouch is formed by 7^th,8^th and 9^th sterna which consist of female gonopore, spumathecal pores and collateral glands.

• A pair of short, anal styles are present in male cockroaches which are absent in female.
• Anal cerci is a pair of jointed filamentous structures present on 10^th segment of both sexes.

Anatomy :-

Digestive system :- Alimentary canal of cockroach show 3 regions :

Foregut :-

1. The preoral cavity is enclosed by mouth parts.
2. Food is tasted and chewed here.
3. Mouth followed by short tube pharynx bends backward and joins narrow, tubular oesophagus.
4. Oesophagus opens into crop followed by conical gizzard.
5. In gizzard grinding of food takes place by cuticular lining first form 6 plates of teeth. Them,well crushed food is passdon done by bristles present in gizzard.

Midgut :-

1. Ring of 7 and 8 blind hepatic caeca is joined to anterior end of midgut. These caeca secrete digestive juice.
2. To protect delicate, cellular lining from injury a permeable membrane i.e. perithrophic is formed around food particles.

Hindgut :-

1. It consist of ileum, colon and rectum.
2. The yellowish thread like structure Molphiglain tubules is joined to superior of ileum. These tubules play role in excretion.

Digestive glands :-

1. It consist of ileum of gland cells in the lining of midgut, hepatic caeca and salivary glands.
2. Salivary glands are located on the sides of crop and open into preocal cavity.

Respiratory system :-

It consist of intense network of trachea that open through spiracles (small holes)present on lateral side of body. Oxygen is carried to all body parts through tracheal tubes subdivided into tracheoles by the process of diffusion.

Circulatory system :-

• Open type blood circulation system is present in cockroaches.
• Haemocoel consist of viscera immersed in blood having colourless plasma and irregular WBCs, such blood vessel is called haemolymph.
• Heart of cockroach consists of elongated muscular tube in the medial plane from throrax to abdomen.

With ostia of either side of heart, differentiated it into chambers.

• These ostia help in entering of blood into heart from sinuses and in pumping of blood from heart to sinuses.

Excretory system :-

• Organ of excretion : malphighian tubules,
• Malphighian tubules is lined by glandular ciliated calls.
• Cockroach is uricotelic as it excretes uric acid as waste product.
• Malphighian tubules absorb nitrogenous waste and convert it into uric acid, excretory organs : Fat body, mephroeyres and urecose glands.

Nervous system :-

• In cockroach, a series of fused segmentally arranged ganglia joined by paired longitudinal connective tissue forms nervous system.
• Cockroach can able to live for one week without head because head holds a bit of nervous system while rest is situated on ventral side of body.

Sense organs :- Antennae, eyes, maxillary palps, labial palps, cerci etc.

• Cockroach have mosaic vision (nocturnal vision), because they are capable of receiving several images of object due to present of 200 hexagonal ommatidia in each eye.

Reproductive system :-

Sexes are separate and distinguishable externally.

Female reproductive organs.

• It consist of 2 large ovaries, located in 2^nd -6^th abdominal segments.
• A group of light ovarian tubules, containing  a chain of developing ova forms each ovary.
• Vagina is formed by union of oviducts of each ovary and opens into genital chamber.
• A pair of sperm theca is present in 6^th segment, opens into genital chamber.

Male reproductive organ

• It consist of pair of tester, locate on each lateral side of 4^th – 6^th abdominal segment.
• Vas deferens is arised from each tertis , which through seminal vesicle opens into ejaculatory duct.
• The Ejaculatory duct open into male Gunapore.
• In 6^th-7^th abdominal segments, mushroom shaped gland is present which act as accessory reproductive gland.
• Phallomere is external genitalia ( chitinous as ymmetrical structure surrounding gonopore of males )
• Spermtophores are the bundles of seminal vesicles which store sperms and discharged them during copulation.
• Sperms are transferred through spermatophores.
• O othecae are the capsules encoring the fertilized eggs.
• It is capsule of dark reddish or blackish brown is colour.
• Length of ootheca  : 8 mm.
• These oothecae are glued to lace of high relative humidity near food source.
• An oothecae is consist of 14-16 eggs and on overage , about 9-10 oothecae is produced by female cockroach.
• Development is through nymphal stage, so the developments pauro metabolus.
• The nymph grows into adult by moulting about 13 times.
• Wing pads are absent in nymph, but present in adult cockroach.

Cockroaches are count in parts because they destroy food and contaminate it.

Also they act as vectors of many disease.