The Neem tree is a tropical tree and is growing in semi-arid climates in Asian countries and in the tropical regions of the western hemisphere. Neem is known since centuries for its natural and comprehensive pest control properties. Indian farmers have been using neem as insecticide for a long time based on traditional knowledge. For example, it was a common practice in rural India to improve the storage of grains by mixing the grain with dried neem leaves.

Neem cake is applied to rice and sugarcane fields against stem borers and white ants since 1930. The mixing of neem leave (2-5%) with rice, wheat and other grains is still practised in some parts of India and Pakistan and farmers in India still put green twigs and leaves in rice nursery beds to produce robust seedling and simultaneously ward-off attack by early pests-leafhoppers, planthoppers, and whorl maggots. 

In the 1960s Indian scientists reported the feeding deterrent property of neem seed kernel suspension against desert locust. Subsequently, several bioactive ingredients (particularly meliantriol and azadirachtin) were isolated from various parts of the tree. These findings aroused worldwide interest in the bioactivity of the neem tree.

Insects become increasingly resistant against traditional pesticides. The costs for developing a new pesticide are high. Moreover, many people all over the world are becoming aware of the fact that food, which is treated with pesticides, is not healthy. New, more environmentally sound pesticides are needed. A promising option are extracts of the neem tree, which is why the United Nations declared the neem tree as the "Tree of the 21st century".

Using neem derivatives for managing pests is a non-violent approach to controlling pests. Neem products work by intervening at several stages of the insect's life. They may not kill the pest instantaneously but incapacitate it in several ways. Neem very subtly employs effects such as repellence, feeding and ovipositional deterrence (influence on the egg laying process), growth inhibition, mating disruption, chemo-sterilisation, etc. These are now considered far more desirable than a quick knockdown in integrated pest management programs as they reduce the risk of exposing pests' natural enemies to poisoned food or starvation. The mentioned effects act as follows: Anti-feedant Neem has anti-taste properties, which results in the reduction of the eating activity of insects.  Repellent The smell of neem repels insects. Growth regulatory effect Neem disturbs the metabolism of insects during various phases of its development. Egg development and hatching is affected and the moulting of larvae is disturbed, which prevents the formation of pupae.  One of the characteristics of neem is its systematic action. Seedlings absorb neem through their roots and transport the active components into the leaves, thus making the whole plant resistant to insects. Neem has a broad spectrum of action, which means that they are effective to a wide range of pests. Scientific research has shown that neem extracts can influence nearly 400 species of insects, belonging to Blattodea, Caelifera, Coleoptera, Dermaptera, Diptera, Ensifera, Hetroptera, Homoptera, Hymenoptera, Isoptera, Lepidoptera, Phasmida, Phthiraptera, Siphonoptera and Thysanoptera, on species of ostracod, several species of mites and nematodes, and even noxious snails and fungi, including aflatoxin-producing Aspergillus  flavus.  Some of  these   pests  are   resistant   to  pesticides,  or  are
inherently difficult to control with conventional pesticides, such as floral thrips, diamond back moth and several leaf miners.  Examples of insects that can be combated with neem are: • Cowpeaweevil; • White fly; • Spotted cucumber beetle; • Green rice leafhopper; • Rice hispa; • Brown planthopper; • Mexican bean beetle; • Cotton bollworm (Helicoverpa armigera); • Colorado potato beetle (Leptinotarsa decemlineata); • Spyni bollworm; • Lesser grain borer; • Gypsy moth; • Rice weevil; • Tobacco hornworm; • Red flour beetle; • Pink bollworm; • Khapra beetle; • Potato tuber moth; • Sorghum shootfly; • Diamond-back moth (Plutella xylostella); • Vegetable leafminer; • Tobacco caterpillar; • Rice galf midge; • Migratory locust; • Red cotton bug; • Desert locust.
These pests are present in a wide range of crops. Neem can be applied in plantation crops, fodder crops, rootcrops, floriculture, horticulture, cereals, pulses, oilseeds, vegetables, gardens, orchards, nursery kitchen gardens, golf courses, potted plants, forestry species, etcetera.