How to Find Butterfly Cocoons

You can find pupal butterflies by searching on and around their host plants. If you use a delicate touch and set up a suitable habitat for the metamorphosing insect beforehand, you can collect a few chrysalises and watch them emerge at your house.

Although people often use the terms interchangeably, cocoons and chrysalises refer to two different things. All lepidopterans -- a group consisting of butterflies, moths and skippers -- emerge from their eggs as wormlike larvae, called caterpillars. Over the next few weeks, the hungry larvae consume the leaves of their host plant. Over time, the caterpillars molt several times to allow for growth; during the process they crawl out of their old skin, revealing a new skin underneath.

After passing through several such molts, the larvae become ready to enter the pupal stage, where the final transition to their adult form will take place. The pupal stage begins with the final molting of their larval skin, which reveals a smooth skin, called a chrysalis -- some authorities use the term chrysalis in reference to the entire pupa, while others use it in reference to the smooth outer skin of the pupa. However, different types of lepidopterans prepare for this process in different ways.

Larval butterflies begin by spinning a small silk pad, which they attach to a branch. They then use this pad as an adhesive, from which they will hang, shed their larval skin and become pupae. By contrast, larval moths begin the process by constructing a silken structure, which completely encloses the animal. Often, they use a leaf to form the basis of their protective encasement. This type of pupa is correctly termed a cocoon. Like moths, most skippers form mothlike cocoons.

Most butterfly larvae specialize in a closely related group of plants -- some only consume a single species. Females seek out and deposit their eggs on or near these host plants, which provides the ensuing offspring with ample food. Accordingly, the best method for finding chrysalises of a given species is by seeking out their host plants.

• Monarch butterfly caterpillars (Danaus plexippus) will consume virtually any species of milkweed (Asclepias spp.), and will consume sand vine (Cynanchum laeve).
  
• Mourning cloak larvae (Nymphalis anitopa) feed on tree leaves, particularly those of willows (Salix spp.), elm (Ulmus spp.) and aspen (Populus spp.).
  
• Spicebush swallowtails (Papilio troilus) consume their namesake plants, spicebushes (Lindera benzoin); but they also will consume sassafras (Sassafras albidum).
  
• Spring azure larvae (Celastrina ladon) prefer flowering dogwood (Cornus floridana), willowleaf meadowsweet (Spiraea salicifolia) and mountain sweet (Ceanothus americana), but they also feed on staghorn sumac (Rhus typhina).
  
• Common buckeye butterfly (Junonia coenia) larvae feed on yellow foxglove (Digitalis grandiflora).
  

Once you have located one or more suitable host plants, you can begin searching for individual chrysalises. Most butterflies suspend their chrysalises from above, so look for cone-shaped, pendulous structures, nestled among the leaves. Take your time and look carefully, as these pupae are often quite cryptic.

If you are unable to locate any chrysalises on the actual host plant, expand your search to include neighboring vegetation. Some larvae disperse from their host plants before pupating, in an effort to avoid predators. Some individuals may move up to 30 feet away from their host plant before pupating.

After finding a suitable chrysalis, note the position in which it is hanging. This is important, as you must suspend the chrysalis in the same orientation when you return home. Gently separate the chrysalis from the plant or tree to which it is attached with your fingers.

Once home with the chrysalis, affix it to the top of a ventilated plastic or glass container with a piece of tape and place it in a safe place where you can observe it easily.