Pupa

A pupa is a special stage in the life of some insects as they change from their young form to their adult form. Insects that have this stage in their life cycle are called holometabolous insects. They go through four main stages: starting as an egg, then becoming a larva (which often looks very different from the adult), then turning into a pupa, and finally emerging as an imago, the adult insect.

During the pupal stage, the insect’s body changes dramatically inside a protective case. This transformation is controlled by special chemicals called hormones in the insect’s body. The process of becoming a pupa is called pupation, and when the insect finishes this stage and comes out of its case, it is called eclosion or emergence.

Pupae can have different names depending on the type of insect. For example, the pupa of a butterfly is called a chrysalis, while the pupa of a mosquito is sometimes called a tumbler. These pupae may also be protected by additional structures like cocoons, nests, or shells.

Position in life cycle

The pupal stage comes after the larval stage and before adulthood in insects that change form completely. During this time, the insect is usually still and does not eat. The insect grows its adult body parts while breaking down its baby body parts.

The pupal stage can last for weeks, months, or even years, depending on the insect and the temperature. For example, monarch butterflies spend eight to fifteen days as pupae. Some pupae rest until the right season to become adults. In cooler areas, they rest during winter, while in warmer places, they rest during dry times.

When the insect is ready to become an adult, it leaves the pupal case. Most butterflies do this in the morning, but mosquitoes usually do it at night. Before leaving, the adult inside is called a pharate. After leaving, the empty pupal case is called an exuvia.

Defense

Pupae are usually still and cannot move, which makes them vulnerable. To stay safe, many pupae are covered with a cocoon, hide in leaves or soil, or stay underground. Some butterflies are protected by ants during their pupal stage. Other pupae can make sounds or vibrations to scare away animals that might harm them. A few species release toxic liquids as a defense. In social insects like bees and ants, the adult insects help protect the pupae.

Types

Pupae, the stage where insects change from young to adult, can be sorted into two main types based on whether they have special mouth parts called mandibles that help them emerge from their casing.

• Decticous pupa – a pupa with these special mouth parts. Examples include insects from groups like Neuroptera, Mecoptera, Trichoptera, and some Lepidoptera families.
• Adecticous pupa – a pupa without these special mouth parts. Examples include insects from groups like Strepsiptera, Coleoptera, Hymenoptera, Diptera, and Siphonaptera.

Pupae can also be sorted into three types based on whether their body parts are free or attached to the body:

• Exarate pupa – body parts are free and not usually inside a cocoon. Decticous pupae are always exarate; some adecticous pupae are as well. (Neuroptera, Trichoptera, Cyclorrhapha of Dipterans, Siphonaptera, most Coleoptera, Hymenoptera, and few Lepidoptera).
• Obtect pupa – body parts are attached closely to the body and are often inside a cocoon. Some adecticous pupae are obtect forms. (Most Lepidoptera, Nematocera and Brachycera of Dipterans, Staphylinidae and Chrysomelidae Coleopterans, many Chalcidoidea Hymenopterans)
• Coarctate pupa – enclosed in a hard outer layer from the stage before pupation, called a puparium. However, the pupa itself is of the exarate adecticous pupal form. (Cyclorrhapha of Dipterans).

Chrysalis

"Chrysalis" redirects here. For other uses, see Chrysalis (disambiguation).

A chrysalis is the pupal stage of butterflies. The word comes from the shiny, golden look of many butterfly pupae, from an ancient word for gold.

When a caterpillar is fully grown, it makes a button of silk to attach itself to a leaf or twig. Then the caterpillar sheds its skin for the last time, and under it is a hard skin called a chrysalis.

Chrysalises are often easy to see because they are showy and formed in open places. Most chrysalides attach to a surface using a special silk pad made by the caterpillar. Inside the chrysalis, the butterfly grows and changes. The adult butterfly comes out of the chrysalis and pumps liquid into its wings to make them bigger.

When a butterfly is ready to leave the chrysalis, it uses a special liquid to soften the shell and sharp claws on its wings to help it escape. After emerging, the butterfly sits on the empty shell to let its wings harden. If the chrysalis is on the ground, the butterfly will find another surface like a wall to rest on.

Moth pupae are often dark and may be hidden underground or in a silk case called a cocoon. Some moth pupae have special ridges that help them move when it's time for the adult to come out.

Pupa, chrysalis, and cocoon are different things. A pupa is the stage between the larva and adult. A chrysalis is usually a butterfly pupa, though some moths look similar. A cocoon is a silk case that moth larvae spin around their pupa.

Cocoon

For other uses, see Cocoon (disambiguation).

A cocoon is a protective covering made of silk by many moths and caterpillars, as well as other holometabolous insect larvae. It shields the pupa during its transformation.

Cocoons can be tough or soft, different colors, and may have layers. Some caterpillars add bits of twigs or leaves to hide their cocoon. The silk from the silk moth is used to make silk fabric. When the insect is ready to leave the cocoon, it either cuts its way out or uses special fluids to soften the cocoon.

Puparium

Some pupae stay inside the outer skin from their last larval stage, and this outer skin is called a puparium. Flies from the group Muscomorpha, insects from the order Strepsiptera, and certain bugs from the Hemipteran family Aleyrodidae all have puparia.