Approximately 150 species of butterflies live in Illinois, but reports suggest that number is decreasing as a result of habitat loss, pesticide use, and pollution. Planting a butterfly garden is a great way to help combat butterfly extinction. Butterfly gardens help maintain a healthy butterfly population by providing food and encouraging reproduction. Adult butterflies eat nectar from plants such as milkweed, blazing star, and goldenrod, while caterpillars eat plants like clovers, parsley, and violets. In addition to a variety of plants, butterfly gardens also require sunlight. Butterflies are cold-blooded, meaning they cannot regulate their own body temperature. To warm up their flight muscles, butterflies perch on a rock or a leaf and sun themselves. Rocks scattered around this butterfly garden provide spaces for butterflies to rest in the sun.