A field study was carried out during the early cropping season (March-May) of 2018 to evaluate the efficacy of Tephrosia vogelii (a plant extract) and some synthetic insecticides (Lambdacyhalothrin, Imidacloprid and Cypermethrin) on the major insect pests of cucumber and also to assess the yield and yield components of the crop under these treatments. The study was conducted at the Western Farm of the Teaching and Research Farm of the Department of Plant Health Management, Michael Okpara University of Agriculture, Umudike. The experiment was laid in Randomized Complete Block Design (RCBD) with five treatments replicated four times. The Treatments included: 300 g of leaf extract of Tephrosia vogelii, 5 ml of Lambdacyhalothrin, 5 ml of Imidacloprid and 5 ml of Cypermethrin. The efficacy of the treatments were evaluated based on the reduction of insects population, mortality rate of pumpkin beetle, percentage number of leaf defoliation, flower damage reduction and fruit weight yield. The results indicated that at 8 Weeks After Planting (WAP) the extract of T. vogelii and Cypermethrin significantly (P<0.05) reduced the population of pumpkin beetles, melon aphids and the highest mortality count of Pumpkin beetle was also recorded in the plots treated with Cypermethrin. At 4 WAP, the population was 11.5 for Cypermethrin-treated plots and 8.5 for T. vogelii-treated plots. These reduced to 1.0 and 5.0 respectively at 8WAP, which translates to 91% and 41% population reductions for Cypermethrin and T. vogelii. The results revealed that the Plant extract was not as effective as the synthetic Cypermethrin. The implication of these results is that T. vogelii can be used as an alternative to the synthetic insecticides for the control of insect pests of Cucumber in low-input farming systems of the tropics.