Experiments were conducted to determine the resistance level of different cultivars and study the efficacy of various synthetic insecticides against red pumpkin beetle ( Aulocohphora foveicollis) at the New Developmental Malakandir Farm, the University of Agriculture Peshawar, during 2018. In the first experimental trial, data were collected on the mean population density of red pumpkin beetle on three cultivars (Desi, Super Green and Madam-560) of cucumber crop. While in the second experiment, three insecticides (Carbaryl, Cypermethrin, Malathion) and an Untreated/Control were used to study the effect of these insecticides on Desi (susceptible) and Madam 560 (resistant) cultivars regarding red pumpkin beetle on cucumber cultivar. Randomized Complete Block Design (RCBD) was used in this experiment. The data on the relevant parameters were recorded at weekly intervals for eleven (1 st experiment) and four weeks (2 nd experiment) i.e. till termination of the experiments. During first experiment, it was observed that significantly lowest population density of red pumpkin beetle (0.82) per plant and highest yield (8981.3 kg ha -1) was observed from Madam 560, while significantly highest mean population density of red pumpkin beetle (4.06) per plant and lowest yield (7313.7 kg ha -1) was obtained from Desi cultivar. Significantly maximum mean number of red pumpkin beetle plant -1 was recorded in the seventh week (29 May) from Desi, Super Green and Madam 560 cultivars with 6.41, 4.50 and 1.62 beetle plant -1, respectively. During the cropping season, mean population density of red pumpkin beetle plant -1 reached its peak in the seventh week (29 May). After 7 th week, a gradual decline was occurred in the mean population density of red pumpkin beetle plant -1. In second experiment, lowest mean population density of red pumpkin beetle adults plant -1 (0.12), area of consumption (3.12 mm 2), percentage weight loss (1.60 %) and highest yield (21555 kg ha -1) was recorded from Madam 560 treated with Carbaryl, while highest mean population density of red pumpkin beetle adult plant -1 (7.09), area of consumption (36.11 mm 2), percentage weight loss (17.27%) and lowest yield (7247 kg ha -1) was recorded from untreated Desi cultivar. It was followed by untreated Madam 560 cultivar where 5.40, 25.92 mm 2, 13.20% and 8766 kg ha -1. Madam 560 is significantly better cultivar than Super Green and Desi, as this cultivar results in lowest population density of red pumpkin beetle and highest yield of cucumber fruit. Carbaryl is significantly better as compared to Malathion and Cypermethrin because it reduces the population of red pumpkin beetle.