The callus tissue of Tagetes erecta maintained on revised Murashige and Skoog's medium (RT) as static cultures showed the presence of insecticidal pyrethrins. The percentage of pyrethrins further increased by feeding the tissue with various concentrations of ascorbic acid. The maximum pyrethrin content (1.68%) was observed in 6 weeks old tissue grown on RT medium supplemented singly with 1000 mg/l of exogenous ascorbic acid. When pyrethrin mixture was screened against Tribolium spp. immediate 'knock down' effect was observed.