Monkeys are omnivores, not herbivores. Generally, the diet of most monkey species includes fruit, leaves, berries, nuts, twigs and bark, but they also consume insects, spiders, eggs and small animals.
Some species use rocks and sticks to crush the shells of seafood prey or to kill small vertebrates. The first evidence of tool use among monkeys was documented with them fishing ants and termites out of trees using sticks and blades of grass. Monkeys are considered a pest species in many parts of the world, as they often eat crops and livestock food in an attempt to capitalize on easily obtained food.