Cocoon vs Pupa
Cocoon and pupa are highly bonded with each other, as one entity being the home of the other. Therefore, the two could sometimes be understood interchangeably, due to the lack of awareness about arthropod lifecycles. This article attempts to explain the difference between cocoon and pupa through discussing their characteristics.
Cocoon
Cocoon is a case that has been created by the secreted saliva or silk by the lepidopteron insect larvae. The presence of cocoon ensures the protection for the developing pupa living inside it. It would be interesting to know that cocoon may be either hard or soft depending on the species of the Lepidoptera insect. However, there are cocoons with a mesh-like makeup, as well. The structure of the cocoon may compose of many layers of silk as well as a couple of layers. The usual colour of a cocoon is white, but that also could vary depending on the species and the environmental characters such as dust. Caterpillars of most of the moth species have ‘hairs’ or setae on their skin, and those are shed at the end of the caterpillar stage and form the cocoon. The protective function of the cocoon is enhanced when the caterpillar had urticating hairs as those would make it itching for the animals that try to touch the cocoon. In addition, there are cocoons with faecal pellets, cut leaves, or twigs attached to the exterior so that the predators do not spot the structure. When the protective strategies are considered, the location of a cocoon is placed has a major role in being saved from predators; hence, most of the cocoons are found underneath leaves, inside crevices, or suspended in leaf litter. The pupa inside the cocoon escapes from it after the development into an adult is completed, and some species dissolve it, some species cut it, and others have a weakened escape line through the cocoon. It would be important to state that cocoons have been a very successful source of income for people when the silk moths are considered.
Pupa
Pupa is an immature stage in the life cycle of holometabolous insects. Pupa is the life stage between larva and adult. It is an immobile form of the lifecycle and lives encased in a cocoon, shell, or a nest depending on the species. Since pupae do not move from place to place, they are susceptible for predation. However, they overcome the predation with hardened shells or camouflaged cases. Due to the encased or immobile nature, some authors state that pupae are inactive, yet there are so many activities taking place during this stage of the lifecycle. Usually the larva does not look the same as an adult in any lifecycle, but pupa transforms the larva into a completely different form. Caterpillar is the larval stage, and the butterfly larva transforms into an attractive butterfly after completing the pupa stage.
Larva and adult are ecologically two different entities with different roles to play in the ecosystem, due to varied food habits and body forms. Therefore, the ecological importance of the pupa stage is enormous. Pupa is referred in many names depending on the animal group such as chrysalis in moths, tumbler in mosquitoes, etc.
What is the difference between Cocoon and Chrysalis?
• Cocoon is a structure while pupa is a stage in the lifecycle of insects.
• Cocoon accompanies the butterfly lifecycle, whereas pupa stages are present in all the holometabolous insects.
• A cocoon does not become anything after the pupa has escaped while pupa becomes an adult.
• Pupa is a life form, but not the cocoon.