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Merian and Metamorphosis

A watercolour of a branch of an unidentified Willow (Salix) with the life cycle of the Puss Moth (Cerura vinula) and the Red Underwing Moth (Catocala nupta). The depiction of both life cycles are adapted from plates 38 and 39

Branch of Willow with Red Underwing and Puss Moths ©

The life cycle of insects had only begun to be understood in Merian’s lifetime. Aristotle (384–22 BC) had argued that insect life was spontaneously generated from rotting matter. His theory dominated until the seventeenth century, when a number of scientists undertook experiments which proved him wrong. Among these was Francesco Redi (1626–97), an Italian biologist, who compared pieces of meat left in sealed and unsealed jars. He discovered that maggots only appeared on the meat left open to the air, proving that insects were not born from rotting matter. This was crucial for the study of metamorphosis, as it challenged the idea that butterflies were new beings, born out of the decay of dead caterpillars.

In Leiden, Jan Swammerdam (1637–80) demonstrated that metamorphosis represented different life stages of the same insect, rather than being the birth of a different animal. Swammerdam’s contemporary Jan Goedart (1617–1688) published a book showing the different stages of insect development in the 1660s. In Amsterdam, Stephan Blankaart (1650–1704) published the Theatre of Caterpillars, Worms, Maggots and Small Flying Creatures (1688), which included illustrations of butterflies from Suriname.

Merian eagerly read these new publications as well as carrying out her own research. She referred to the work of Swammerdam, Goedart and Blankaart in her own publications, and corresponded with others working in the field. Among these was James Petiver (c.1665–1718), a London apothecary who studied butterflies and whom she relied on to promote her work in Britain.