Field trials on evaluation of four insecticide formulations for the management of flowering and post flowering insect pests of cowpea were conducted in two locations (IAR Research Farm Samaru, Zaria, Kaduna State (Lat.11o 111N and 7o 381N) and Wase, in Minjibir local government of Kano State (Lat. 12 100 60.001 and 8 400 0.001 E), under rainfed conditions in the Northern Guinea Savannah and Sudan Savannah of Nigeria respectively. Four insecticide formulations: Chlorpyrifos, Chlorpyrifos plus, Dimethoate and Imidacloprid. There was a standard check (Cyperdicot; 250+30 g a.i./ha) and an untreated control. The treatments were arranged in a randomized complete block design (RCBD) replicated three times. Population of thrips, Megalurothrips sjostedti Tryb, Maruca. vitrata and Clavigralla. tomentosicollis were sampled 24 hours before and after each spray for three weeks between 7.00 and 8.00am. The damage was assessed by counting the number of aborted flowers/plot; seed damage indices (Sdi) was determined by sorting the seed lot from each plot into 3 categories. The results showed that all the four insecticides effectively reduced the population and infestation of insect pests as well as increased the yields compared to untreated control. Most of the insecticides differ significantly from the standard check (Cyperdicot). The various levels (concentrations) 0.5, 1.0 and 1.5 l/ha were similar in their performance in reducing insects' population and infestation, pod and seed damage. Therefore the lower concentration range of 0.5-1.0 l/ha should be used so as to minimise cost and reduce risk of environmental pollution among other hazards. Application of Imidacloprid at 105 g a. i./ha (1.5 l/ha) with almost hundred per cent reduction was most effective in the control of C. tomentosicollis at both locations compared with other insecticide treatments. While Chlorpyrifos at 240 (0.5 l/ha) and 720 g a.i./ha (1.5l/ha) resulted in the highest number (176.00 and 135.33) of pods produced at Samaru and Wase. Chlorpyrifos at 240 g a.i. / gave highest significant grain yield of cowpea in both location