Identifying Insect Cocoons in Your Landscape and Garden

Many insects create a cocoon for protection during an early stage of development, called the pupal stage, in which they dramatically transform from an adolescent larva (such as a caterpillar) to their adult form (such as a butterfly). This is called metamorphosis. When encountering cocoons in your landscape and garden, it’s important to identify the cocoon type to be sure you’re not harming a potentially beneficial and beautiful insect that’s part of your landscape’s ecosystem. Insects typically start the pupal stage in fall and metamorphose over winter, emerging as an adult in spring. The structure shown here, technically called a chrysalis (more on that in a bit), houses a developing butterfly.

To identify a cocoon, first take note of a few key things: cocoon shape, material, color, and placement in the garden or landscape, as well as time of year. Cocoons may be hanging from trees but they may also be tucked into shrubs, brush or piles of leaves. You can also observe what insects are nearby, which serves as a clue to what’s inside. Wondering what to do with a cocoon you’ve spotted? As with most insect interaction in your garden, it’s best to do nothing if you don’t have good identification — and good reason — to do something. Just observe at first. This cozy cocoon belongs to a bagworm pupa.

Most moths create cocoons of silk. Moth caterpillars spin the silk to make their cocoons, producing the silk through a tubelike “spinneret” located near their mouth. Moth cocoons can be oval-shaped and hang from trees, but they can also be found in other locations. The cocoons typically start out white and mature to brown, but they may also be covered in other natural materials like dead leaves, as is often the case with Luna moth cocoons. To encourage Luna moth (and other beneficial insect) populations, leave some of the fall leaves in your yard over winter. Here, silk moths emerge from a silky cocoon.

While they’re very similar, butterflies don’t actually create cocoons like moths do. For their pupa stage, butterflies develop a chrysalis, which is a hard case surrounding the developing butterfly. Like a moth cocoon, you will often spot a butterfly chrysalis hanging from a tree, but it will more likely be green — easy to mistake for a fresh leaf, though it may also be camouflaged by dead leaves, as is the case with Swallowtail butterflies. Butterfly chrysalises become translucent through the pupal stage as the caterpillar metamorphoses into a butterfly, and you can sometimes see the butterfly inside. In this photo, the monarch’s wings are visible just before hatching from the chrysalis.