In cool climates, most species of Lepidoptera
have an annual cycle.
Different species have different periods
in this cycle as Caterpillars.
These are tuned to the progress of the seasons
in the area where they live.
For Lepidoptera species that overwinter as pupae, adults, or eggs, the Caterpillars hatch and feed in spring or autumn. These Caterpillars stay only as Caterpillars for two to three weeks.
A few species overwinter as Caterpillars, and these species can stay as Caterpillars for many months.
At the end of their Caterpillar stage, Lepidoptera pupate for a period. For the species that overwinter as pupae, this stage can last many months. For other species this stage can last two to three weeks.
In tropical climates or warm years, many species have two generations in one year, and both the Caterpillar and pupal stages are each just two to three weeks.
(updated 26 April 2012)