Casulos

Casulos, in entomology, are the pupal stages of many Lepidoptera, including butterflies and moths. During this period the larva is transformed into an adult. Casulos can take two main forms: a chrysalis, which is a hardened shell formed from the larval skin or pupa itself, and a silk cocoon, spun by the larva around the pupa. Some species develop an exposed pupa with little or no cocoon, protected instead by shed exoskeletons or surrounding plant material.

The transition to the casulo marks a period of immobility while transformation occurs. Inside, larval tissues are broken down and reorganized into the structures of the adult insect. Metamorphosis is completed when the adult emerges from the casulo. The pupal stage is typically non-feeding and lasts from days to months, depending on the species and environmental conditions such as temperature and humidity.

Pupation sites vary widely. Some species form casulos on vegetation or in leaf litter, others underground, within stems, or inside fruit. The casulo is a crucial part of the life cycle, enabling the dramatic transformation that yields flying adults capable of reproduction.

In economic and ecological contexts, casulos are notable for silk production in some species, such as the silkworm Bombyx mori, whose cocoon is harvested for silk. In many other species, the pupal stage represents a vulnerable period that influences pest management and conservation strategies.