Insect feeding on plants (herbivory) is a major ecological interaction best documented by assessing the intensity and variety of herbivore damage along latitudinal gradients. It is unknown if insect-herbivore latitudinal gradients existed in deep time. An ideal setting for an ancient latitudinal gradient is the north-to-south trending continent of Laramidia in western North America during the Late Cretaceous 75 million years ago. If so, insect-herbivore latitudinal gradients may be ancient.