A life and fecundity table has been constructed for Brevipalpus phoenicis, a serious pest of plantation crops, and various demographic parameters have been calculated. Although this mite has been found to possess a low growth rate (rm = 0.127), it possesses high rates of survival even in its senescence. Under constant experimental conditions the net reproduction rate is 33.2 eggs/mite, the generation time is 27.6 days and the population doubles once in 5.5 days. The stable age profile of the population is distributed as 74.9%, 19.24% and 6.07% of eggs, immatures and adults, respectively. Another aspect considered in this paper is the evolution of the population in function of an effective initial population of 10 individuals. This mite takes a longer time to reach constant growth rate and stable age distribution (156 days), however, the population growth is astronomical. The damage caused by them passes beyond the economic injury level within 34 days by an effective initial population of 10 mites in a tea bush having 100 leaves. This suggests an earlier intervention to check the population. The demographic analysis reveals that the following five aspects of its life history, namely high survival and fertility rates, reproductive intensity in the prime youth, lack of diapause, parthenogenetic mode of reproduction and euryphagy on perennial crops, are of major importance. Reasons for the importance of these characteristics are also discussed.

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The phenomenon of phase variation brought about by crowding has been proven to be an adaptive character for insects like locusts. Observations made on a cohort of Bvecipalpus phoenicis (Geijskes) in groups of 50 individuals revealed that grouping shortens the developmental time and total life span and reduces the capacity for oviposition.This enables one to postulate a new hypothesis that during an epidemic outbreak and in the initial phase of colonisation the mites live longer and produce more eggs when the density of the population is lower until the population reaches a threshold level of crowding and uice zrersa. This phenomenon of phase variation brought about by the group effect is an adaptive character in the sense that when the density of the population is higher, the mites develop faster before the available food is exhausted.