A field trial was conducted during 2007-2008 crop season to study the effect of castor as a trap crop in cotton agroecosystem in relation to major insect pests. The treatments were 5, 10 and 15 rows of Bt cotton interspersed each with 1 row of castor, respectively, sole crop of Bt cotton and castor. Based on the pooled data, the treatment comprising of 10 rows of Bt cotton interspersed with 1 row of castor registered low incidence of jassids.