Butterflies have more enemies than most of us imagine.
Butterfly enemies begin with simple predators. There are predators that eat butterfly and moth eggs, caterpillars, chrysalises, and adults. Some are hunted and eaten, as this Monarch was captured and eaten by a dragonfly. Others are accidentally eaten, such as a cow grazing on plants in a field or a grasshopper eating leaves of a plant.
Parasitoids eat butterfly eggs, caterpillars, and chrysalises from the inside out. Tachinid flies, chalcid wasps, trichogramma wasps, braconid wasps, and many other parasitoids kill many butterflies in their pre-adult stages.
Man kills many butterflies, from egg through adult. Farmers understandably need methods to increase crop production to keep up with demand and reduce prices. Homeowners need foundations sprayed with termite spray. Automobiles kill tens of thousands of butterflies that were flying across highways.
Development, bringing our schools, hotels, roads, and other essential (and non-essential) land clearing, rarely focuses on replanting or protecting habitat and host plants.