Everything about Pupa totally explained
A
pupa (
Latin pupa for doll, pl:
pupae or
pupas) is the life stage of some
insects undergoing transformation. The pupal stage is found only in
holometabolous insects, those that undergo a complete
metamorphosis, going through four life stages;
embryo,
larva, pupa and
imago. (For a list of such insects see
Holometabolism).
The pupae of different groups of insects have different names such as
chrysalis in the
Lepidoptera and
tumbler in
mosquitoes. Pupae may further be enclosed in other structures such as
cocoons,
nests or
shells.
Position in life cycle
In the
life cycle of an insect the pupal stage follows the
larval stage and precedes
adulthood (
imago). It is during the time of pupation that the adult structures of the insect are formed whilst the larval structures are broken down. Pupae are inactive, and usually
sessile (not able to move about). They have a hard protective coating and often use
camouflage to evade potential predators.
Duration
Pupation may be brief, for example 2 weeks as in
monarch butterflies, or the pupa may enter
dormancy or
diapause until the appropriate season for the adult insect (in
temperate climates pupae usually stay dormant during winter, in the
tropics pupae usually do so during the
dry season).
Emergence
Insects emerge (
eclose) from pupas by splitting the pupal case, and the whole process of pupation is controlled by the insect's
hormones. Most butterflies emerge in the morning. In mosquitoes the emergence is in the evening or night. In
fleas the process is triggered by vibrations that indicate the possible presence of a potential host.
Structure
In some insect orders the appendages such as legs and proboscis are free and visible in the pupal stage. Such pupae are termed as
exarate and examples are seen in the
Hymenoptera. In many others the pupa is a tight and compact shell with all the appendages tightly packed within and these are termed as
obtect. The familiar
lepidopteran chrysalis is obtect. Another form has the appendages visible, but covered within a shell. In some cases the covering is formed by the integument of the last larval instar also known as the
puparium. Such pupae are termed as
coarctate and are found in many of the
diptera. Some exarate pupae such as those of the
neuroptera also have movable mandibles attached to the head. Such pupae are termed
decticous. In most other insects the mandibles are immovable and such pupae are termed
adecticous.
Defense
Pupae are usually immovable and are largely defenseless. To overcome this, a common feature is concealed placement. Some species of
Lycaenid butterflies are protected in their pupal stage by ants. Some species of pupae are capable of making sounds or vibrations to scare potential predators. A few species use chemical defenses including toxic secretions. The pupae of social
hymenopterans are protected by adult members of the hive.
Chrysalis
A
chrysalis (
Latin chrysallis, from
Greek χρυσαλλίς =
chrysallís, pl:
chrysalides) or
nympha is the pupal stage of
butterflies. The term is derived from the metallic gold-colouration found in the pupae of many butterflies referred to by the
Greek term χρυσός (
chrysós) for gold.
Because chrysalids are often showy and are formed in the open, they're the most familiar examples of pupae. Most chrysalids are attached to a surface by a
Velcro-like arrangement of a
silken pad spun by the
caterpillar and a set of hooks (
cremaster) at the tip of the pupal
abdomen.
Like other types of pupae, the chrysalis stage in most butterflies is one in which there's little movement. However, some butterfly pupae are capable of moving the abdominal segments to produce sounds or to scare away potential
predators. Within the chrysalis, growth and differentiation occur. The adult butterfly emerges (ecloses) from this and expands its wings by pumping
haemolymph into the wing veins. This sudden and rapid change from pupa to imago is called
metamorphosis.
When the butterfly emerges from the chrysalis, usually it'll sit on the empty shell in order to expand and dry its wings. However, if the chrysalis was near the ground (such as if it fell off from its silk pad), the butterfly would find another vertical surface to rest upon and dry its wings (such as a wall or fence).
Moth pupae are usually dark in color and either formed in underground cells, loose in the soil, or their pupa is contained in a protective
silk case called a
cocoon.
Aurelia is an old synonym of chrysalis from which is derived the term
aurelian; one who studies the emergence of butterflies from chrysalids.
Cocoon
A
cocoon is a casing spun of
silk by many
moth caterpillars and numerous other
holometabolous insect
larvae as a protective covering for the pupa.
Cocoons may be tough or soft, opaque or translucent, solid or meshlike, of various colors, or composed of multiple layers, depending on the type of insect larva producing it. Many moth caterpillars shed the larval hairs (
setae) and incorporate them into the cocoon; if these are
urticating hairs then the cocoon is also irritating to the touch. Some larvae attach small twigs, fecal pellets or pieces of vegetation to the outside of their cocoon in an attempt to disguise it from predators. Others spin their cocoon in a concealed location - on the
underside of a
leaf, in a
crevice, down near the base of a
tree trunk, suspended from a twig or concealed in the
leaf litter.
Insects that pupate in a cocoon must escape from it, and they do this either by the pupa cutting its way out, or by secreting fluids that soften the cocoon. Some cocoons are constructed with built-in lines of weakness along which that'll tear easily from inside, or with exit holes that only allow a one-way passage out; such features facilitate the escape of the adult insect after it emerges from the pupal skin.
Image:Caterpillar making cocoon2.jpg|An Emperor Gum Moth caterpillar spinning its cocoon.
Image:Actias luna pupa 2 sjh.JPG|Luna moth cocoon and pupa.
Image:Actias luna cocoons sjh.JPG|Assortment of Luna moth cocoons.
Image:Actias luna emergence sjh.gif|Luna moth emerging from silk cocoon.
Image:Actias luna pupa sjh enhanced.JPG|Luna moth pupa removed from cocoon.
Image:Chrysalis5504.jpg|Chrysalis of Gulf Fritillary in Georgetown, South Carolina
Image:Pupation_-_Inachis_io.jpg|Pupation of Inachis io
Image:Monarch Butterfly Chrysalis.JPG|Monarch Butterfly chrysalis
Further Information
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