1. PESTS AND CATEGORIES OF PESTS
PEST : Any Insect or animal or plant ,that becomes a source of trouble, and cause significant loss to the welfare of the human beings is called as Pest.
No of insect sp in the World are 30 lakhs (Sylvestry,1926).
No of insect sp in India are lakhs (Metcalf,2940).

2. CATEGORIES OF PESTS
REGULAR PESTS : Are those pests that occurs most frequently on a crop and have close association with that crop e.g Aphids on cotton, Thrips on chilli etc
OCCASIONAL PESTS : Are those that occurs rather infrequently and have no close association with a particular crop e.g. Case worm on paddy, Mealy bugs on cotton etc.
SEASONAL PESTS : Are those that occurs mostly during particular part (Season ) of the year .e.g. Aphids on Safflower in Rabi, Gross hoppers on rice in Kharif etc.

3. PERSISTENT PESTS : are those that occurs on crop almost throughout the year. e.g. Scales and Mealy bugs on number of crops.
SPORADIC PESTS : Insects which occurs in few isolated localities .e.g Rice ear head bug, Slug caterpiller etc.
EPIDEMIC PESTS : Are those that occurs in a Severe form in a region or locality at a particular season or time e.g. jawar Midge, locust etc.
ENDEMIC PESTS : Are thoes that occurs regularly, and confined mostly to a particular area or locality e.g. White grub in Nanded, Spingid moth in mehkar area of buldana etc.

4. CATEGORIES OF PESTS CONTD…
KEY PESTS : These are the most severe and damaging pests. The GEP lies well above DB and EIL. Artificial control measures may bring the pest below EIL, but it again rises rapidly and repeated sprays required. E.g.Cotton boll worms, Gram pod borer etc.
MAJOR PESTS : These are the regular pests causing appreciable damage to crops. Here the GEP is close to EIL and in some cases both may essentially be at the same level.Thus population crosses EIL repeatedly and frequent control measures are necessary. E.g. Sugarcane White fly, rice stem borer etc.

5. MINOR PESTS : The GEP lies below EIL and DB
MINOR PESTS : The GEP lies below EIL and DB . Under favorable environmental conditions, the population may cross EIL and DB for usually a short Interval. E.g. Grey weevil on cotton, rice hispa on rice.etc.
POTENTIAL PESTS : These insects cause no damage under prevailing conditions. But sometimes, the use of insecticides may kill one or two of them, thereby releasing the pressure of competitionand turning them in to pests.e.g. Spodoptera litura on cotton and sunflower under North Indian condition, army worm on wheat etc.

6. CATEGORIES OF PESTS CONTD…
NEGLIGIBLE PESTS : If an insect causes a losses less than 5 % of yield, the infesting pest is called as Negligible pest e.g. Leaf minor on cotton, lear roller on pigeonpea etc.
‘r’ PESTS : ‘r’ pests are opportunist, exploiting temporary habitats ,having a high rate of population increase, short generation time, strong dispersal and host finding abilities .e.g. H. armigera, S. litura etc. ‘

7. ‘k’ PESTS : ‘k’ pests by contrast ,have lower rates of increase than ‘r’ pests, greater competitive ability, more specialized food preferences and by comparison with other members of the same TAXA, greater size. e.g.Codling moth, tse-tse fly etc.
‘r’ and ‘k’ PESTS : In between ‘r’ pests and ‘k’ pests (Southwood,1997)