German cockroach (Blattella germanica)
The German cockroach prefers warm humid environments i.e., kitchens/bathrooms.
The German cockroach is very successful due to the large number of eggs (up to 32) per ootheca . The female carry’s the ootheca with her until just before hatching. They will sometime be seen to eject the ootheca if they come in contact with insecticide as a sort of defence mechanism as the ootheca is impervious to insecticide.
The nymphs when hatched are very small in size so they can conceal their self very easily. They can use their size and mobility to quickly move away from treated surfaces. The speed at which the German cockroach grows is dependent on its living temperature conditions. The growth from nymph to adult could take anywhere between 6 weeks to 6 months.
Oriental cockroach (Blatta orientalis)
The oriental cockroach is almost double the size of a German cockroach at around 20-24mm long. This variety of cockroach is usually found in areas like cellars, ducting, kitchens, boiler rooms and sewage areas.
The oriental cockroach carries an ootheca with around 16 eggs. The nymphs take between 10 months to 2 years to grow to adult size.
This species of cockroach cannot climb smooth surfaces but would be able to climb something as rough as brickwork.
