For projects on the life cycle of Monarch butterflies, students need an enclosure or cage, caterpillars and milkweed. Cages can be purchased in a variety of sizes from small single caterpillar to large multiple caterpillar enclosures. Plastic containers may also serve as cages for keeping the caterpillars during the pupae stage. Living Monarch caterpillars are purchased through online suppliers. Milkweed is a common plant throughout North America with more than 100 known species. While dangerous to humans, milkweed is the lone source of nutrition for Monarch caterpillars. Depending on the season, milkweed can be collected, purchased or grown to help along the growth of the caterpillars into butterflies.
Common milkweed is most abundant in the fall and may be collected and stored to ensure a continued supply for science projects in the late fall or early winter. When naturally grown milkweed is not available, students cultivate a small garden of tropical milkweed for feeding the caterpillars. Plants should be at least 4 months old before being used for butterfly projects and each caterpillar needs at least one plant a piece to maintain it through the growth cycle. Whole plants or cuttings may be placed in the butterfly cage.
Prior to the pupae stage of development, the caterpillar's skin begins to tighten and will be shed five times before it enters the chrysalis. Once caterpillars are ready to enter the pupae stage of the life cycle, they will attach to an area of the cage with silk and begin pupation. A chrysalis shell develops around the caterpillar that turns from opaque green to clear as the butterfly forms. When hatching is triggered, the process is complete in just 10 to 15 minutes. The freshly born butterflies hold to the side of a plant while they stretch their delicate wings and allow them to dry. A digital video recorder can be set up outside of the butterfly cage to catch the full process for study or display during the science fair.
During the observation portion of the project, students can perform additional activities related to the growth of the butterflies. For example, each year Monarchs migrate with the seasons, appearing across the United States during the warmer months before heading south for the winter. Students can trace the migratory pattern of the butterfly through online programs. During the growth cycle students may also experiment with the habitat of the cage by comparing effects of reducing or increasing light exposure during the chrysalis stage.