In digestive system of cockroach, the crop is followed by the gizzard or proventriculus which has an outer layer of thick circular muscles and thick inner cuticle forming six highly chitinous plates called "teeth". Gizzard helps in the grinding of the food particles.

1. Earthworms can be used for recycling of waste food, leaf, litter and biomass to prepare a good fertilizer in container known as wormery or wormbin.
2. It makes superior compost than conventional composting methods.

1. Vermiwash is a liquid manure or plant tonic obtained from earthworm.
2. It is used as a foliar spray and helps to induce plant growth. It is a collection of excretory products and mucus secretion of earthworms along with micronutrients from the soil organic molecules.

1. Artificial rearing or cultivation of earthworms involves new technology for the betterment of human beings. This process is known as Vermiculture.
2. The process of producing compost using earthworms is called Vermicomposting.

Vermiculture, vermicomposting, vermiwash and wormery are inter-linked. and interdependent processes, collectively referred as Vermitech.

Development is said to be direct if no larva is formed in the life cycle of an organism. Eg: Earthworm.

A pair of prostate glands lies in the 18^th - 19^th segments. The secretion of the prostate gland serves to cement the spermatozoa into bundles known as spermatophores.

(i) Ommatidia are the visual units of compound eyes of cockroach.
(ii) Each ommatidium is functional as an eye unit.
(iii) Photoreceptors are dorsally found.
(iv) Each compound eye consists of 2000 simple eyes called ommatidia.
(v) All the visual images captured by ommatidia are made into a single coherent picture by supra oesophageal ganglion (brain).

(i) Four species of cockroachs destroy food and contaminate them with their offensive odour.
(ii) Their mere presence is a sign of unhygenic condition and they are also known as the carriers of many bacterial diseases.
Eg: The allergen of cockroach can cause asthma or hypersensitivity among the human beings.

(i) The dried solid excreta rich in urea released by pygidium of earthworms are earthworm casts or worm castings or worm pellets
(ii) They are released by anus due to the function of nephridia
(iii) Released worm castings increase the fertility of soil for plant growth
(iv) Worm castings are less released during rainy season