Rice is the staple food of Bangladesh grown in Aus, Aman and Boro seasons. Most of the cultivable lands are occupied by rice in Aman season. Insect pests are the major concern of rice cultivation. Different species of insects are found in rice field based on growing seasons and localities. The study was conducted in T. Aman season around Patuakhali Science and Technology University (PSTU) to know the prevalence and abundance of insect pests in T. Aman rice ecosystem. Sweeping net was used to collect the insect samples. The prevailing insect pests were rice bug (Leptocorisa acuta Thun.), green leafhopper (Nephotettix virescens Dis.), brown planthopper (Nilaparvata lugens Stal), short horned grasshopper (Hieroglyphus daganensis Krauss), long horned grasshopper (Tettigonia viridissima Krauss), leaf roller caterpillar (Cnaphalocrocis medinalis Guenee), green horned caterpillar (Melanitis leda Lin.), yellow stem borer (Scirpophaga incertulas Walker), rice caseworm (Parapoynx stagnalis Zeller), rice pollen beetle (Chiloloba acuta Wied.) and rice skipper (Pelopidas mathias Fab.). Among these pests, green leafhopper (51.96% relative abundance) and brown planthopper (21.79% relative abundance) were the most abundant while rice pollen beetle was the least abundant (0.565%). These insect pests belong to 9 different families under the orders of Hemiptera, Orthoptera, Lepidoptera and Coleoptera.