Many people will remember, from their school science lessons, diagrams like this showing the process by which butterflies develop, from egg to caterpillar to chrysalis to fully grown butterfly. The process is called metamorphosis.

What is not usually remembered is that an understanding of this process (seen in several insect species, and in frogs) did not really develop until the 18^th century. Before that, people tended to think that creatures such as butterflies and frogs emerged fully formed – a process known as ‘spontaneous generation’. It was not until the work of Louis Pasteur in the 1860s that this theory was finally put to rest. Yet it had been severely questioned rather earlier than this, and, quite remarkably for the times, by a woman.

Maria Merian was a German naturalist who lived in the 17th and early 18th centuries. She was born on April 2, 1647, in Frankfurt, Germany and, from an early age, displayed an interest in insects and their life cycles. Her family had a strong artistic background, and she received training in painting and illustration. Her skills as an artist would later become an essential component of her scientific work.

As a young girl, Maria began collecting and studying insects, particularly butterflies and moths, and this early fascination led to her most significant achievements and her expedition to Suriname (then known as Dutch Guiana) in South America in 1699. This journey was remarkable because, during her time, it was quite uncommon for a woman to undertake such scientific expeditions. During the expedition, she observed and meticulously documented the life stages of various insect species, including butterflies and moths, which resulted in her influential publication “Metamorphosis insectorum Surinamensium” (Metamorphosis of the Insects of Suriname).

In her publication, Maria Merian accompanied her detailed observations with beautifully illustrated plates. Her artistic talent helped accurately depict the insects’ life stages, attracting the attention of fellow naturalists and scientists.

In this plate, she depicted the metamorphosis

of the garden tiger moth, its plant host,

and parasitic wasps.

Merian’s work challenged the prevailing belief at the time that insects spontaneously generated from other substances. She demonstrated that insects, particularly butterflies and moths, undergo complete metamorphosis—egg, larva, pupa, and adult stages. Her work laid the foundation for modern entomology and contributed significantly to the understanding of insect life cycles and metamorphosis. Her detailed and accurate observations have had a lasting impact on the study of insects and natural history.

As a female scientist in the 17th century, Maria faced challenges and gender barriers in the male-dominated scientific community. Despite these obstacles, her dedication and achievements earned her respect among her contemporaries. She passed away on January 13, 1717, in Amsterdam, Netherlands, leaving behind a lasting legacy in the scientific world.

Among her more significant contribution to science is the pairing of each larva type with the plant on which it fed. She collected and kept caterpillars and conducted experiments to confirm her observations. She noted “caterpillars which fed on one flowering plant only, would feed on that one alone, and soon died if I did not provide it for them.” She documented that some caterpillars would feed on more than one plant, but some only did so if they were deprived of their preferred host plant.

Portrait of

Maria Sibylla Merian

from 1679