Cockroach (তেলাপোকা)

Cockroach

Cockroach is also called roach, any of about 4,600 species of insects that are among the most primitive living winged insects, appearing today much like they do in fossils that are more than 320 million years old. 

The word cockroach is a corruption of the Spanish cucaracha. The cockroach is characterized by a flattened oval body, long threadlike antennae, and a shining black or brown leathery integument. The head is bent downward, and the mouthparts point backward instead of forward or downward as is the case in most other insects. The male usually has two pairs of wings, whereas the female, in some species, is wingless or has vestigial wings. The female produces eggs in egg cases (called oothecae). These are sometimes held protruding from her body or may be glued in protected areas. After the female deposits an egg case, the soft white nymphs emerge. As their exoskeleton hardens, it turns brown in colour. The structure and large size (certain species have a wingspread of more than 12 cm (4.7 inches) of cockroaches have made them objects of interest in the biological laboratory.

We often find out the following type of Cockroach-

1. American Cockroach

2. Oriental Cockroach

3. Smoky-brown Cockroach

4. German Cockroach

5. Brown Banded Cockroach

6. Madagascar Hissing Cockroach

1. The American cockroach (species Periplaneta americana), a native of tropical and subtropical America, is 30 to 50 mm (up to about 2 inches) long, is reddish brown, and lives outdoors or in dark heated indoor areas (e.g., basements and furnace rooms). During adult life, a period of about 1.5 years, the female deposits 50 or more oothecae, each containing about 16 eggs that hatch after 45 days. Nymphal life lasts from 11 to 14 months. The American cockroach has well-developed wings. However, most species are not good flyers.

2. The Oriental cockroach (Blatta orientalis) is considered one of the filthiest of household pests. It is oval, shiny black or dark brown, and 25 to 30 mm (1 to 1.2 inches) long, with a life cycle similar to that of the American cockroach. The male has short fully developed wings, and the female has vestigial wings. This cockroach has been distributed by vehicles of commerce from its Asiatic origins to all the temperate regions.

3. The brown-banded cockroach (Supella longipalpa) resembles the German cockroach but is slightly smaller. The male has fully developed wings and is lighter in colour than the female, whose wings are short and nonfunctional. Both sexes have two light-coloured bands across the back. The adult life span is about 200 days, and there may be two generations annually. Eggs may be deposited in clothes, wood molding, or cracks in the floor. With the advent of heated buildings, this cockroach became established in cooler climates.

4. The German cockroach (Blattella germanica), a common household pest sometimes erroneously called a waterbug, is light brown with two dark stripes on the prothoracic region. The female produces the ootheca three days after mating and carries it for about 20 days. Three or more generations may occur yearly. Because it is small (about 12 mm [less than 0.5 inch] long), this cockroach often is carried into homes in grocery bags and boxes. It has spread throughout the world by ship. Abundant around the water pipes of the Croton Aqueduct in everywhere in the world, this cockroach became known as the Croton bug.

Wood roaches are not domestic pests. The Pennsylvania wood cockroach (Parcoblatta pennsylvanica) is found under logs and stones in northern latitudes. The male and female are so different in appearance that they were once considered separate species. The male, 15 to 25 mm (0.6 to 1 inch) long, has wings that extend past the abdomen. The female is smaller and has much shorter wings. The brown-hooded cockroach (Cryptocercus punctulatus) digests wood with the aid of certain protozoans in its digestive tract.

Since the 19th century, scientists believed that cockroaches were an ancient group of insects that had a Devonian origin, according to one hypothesis. Fossil roachoids that lived during that time differ from modern cockroaches in having long external ovipositors and are the ancestors of mantises, as well as modern blattodeans. As the body, hind wings and mouthparts are not preserved in fossils frequently, the relationship of these roachoids and modern cockroaches remains disputed. The first fossils of modern cockroaches with internal ovipositors appeared in the early Cretaceous. A recent phylogenetic analysis suggests that cockroaches originated at least in the Jurassic.

The evolutionary relationships of the Blattodea (cockroaches and termites) shown in the cladogram are based on Eggleton, Beccaloni & Inward (2007). The cockroach families Lamproblattidae and Tryonicidae are not shown but are placed within the superfamily Blattoidea. The cockroach families Corydiidae and Ectobiidae were previously known as the Polyphagidae and Blattellidae.

Distribution and habitat of cockroach:

Cockroaches are abundant throughout the world and live in a wide range of environments, especially in the tropics and subtropics. Cockroaches can withstand extremely cold temperatures, allowing them to live in the Arctic. Some species are capable of surviving temperatures of −188 °F (−122 °C) by manufacturing an antifreeze made out of glycerol. In North America, 50 species separated into five families are found throughout the continent. 450 species are found in Australia. Only about four widespread species are commonly regarded as pests.

Cockroaches occupy a wide range of habitats. Many live in leaf litter, among the stems of matted vegetation, in rotting wood, in holes in stumps, in cavities under bark, under log piles and among debris. Some live in arid regions and have developed mechanisms to survive without access to water sources. Others are aquatic, living near the surface of water bodies, including bromeliad phytotelmata, and diving to forage for food. Most of these respire by piercing the water surface with the tip of the abdomen which acts as a snorkel, but some carry a bubble of air under their thoracic shield when they submerge. Others live in the forest canopy where they may be one of the main types of invertebrate present. Here they may hide during the day in crevices, among dead leaves, in bird and insect nests or among epiphytes, emerging at night to feed.