Some good insects eat pest insects , such as lady beetles ( or ladybirds or ladybugs ) eating aphids . Insectivorous insects , or insects which feed on other insects , are beneficial to humans because they eat insects that could cause damage to agriculture and human structures . For example , aphids feed on crops and cause problems for farmers , but ladybugs feed on aphids , and can be used as a means to get significantly reduce pest aphid populations .