A field survey was conducted at Ajiwa irrigation site of Katsina State, Nigeria with a view of investigating the occurrence of insect pests attacking some vegetables cultivated by farmers of the area. Pest samples were collected from five different vegetables (tomato, spinach, lettuce, sweet pepper and onion) which were identified as aphid (Homoptera), cutworm (Lepidoptera), hornworm (Lepidoptera), Pepper maggot (Diptera) and thrips (Thysonaptera). It is revealed that tomato had the highest (30.47%) prevalence, while onion had the least (5.42%) pest prevalence. The results show that the pest prevalence was significantly (p<0.05) different between the vegetable types cultivated at the study area. Both larval and adult stages of the pests were found attacking different parts of the vegetables. Aphid attacked leaves of both tomato and sweet pepper with the highest (24.40) number on tomato. Thrips were the least (5.80) among all the insect pests identified and were the only ones found attacking onion. Members of the Order Homoptera (aphids) were the most abundant pests infesting the leaves of tomato and sweet pepper, while the Thysanoptera had the least (5.81) number of representative (thrips) per vegetable found on the leaves of onion. Out of the farmers interviewed, 50.00% used chemical method, while only 10.00% employed the use of botanicals. Some (12.00%) combined some of the methods such as chemical and cultural, chemical and botanicals, etc, in controlling pests of vegetables at the study area. Identifying insect pests infesting vegetables cultivated at Ajiwa irrigation site could help in proper control measures which would promote vegetable production in the area.