Abstract: Effects of neem oil on mating and oviposition behaviour of C. chinensis grown on azuki bean under laboratory conditions were studied. Mating frequency, copulation duration, fecundity and survivorship of the next generation progenies were significantly decreased by neem oil. Mating frequency was always found to be lower in the oil-treated pair than in the control pair, but it was increased with time after the oil application. A lower mating frequency and shorter copulation duration results in lower fecundity and lower emergence rate. Fecundity and emergence rate were always lower in oil-treated conditions. The effects of neem oil were always greater on male-treated pairs than on female-treated pairs.