Blumenbuch series. Merian's process of creating her art used vellum which she primed with a white coat. Because of the guild system women were not allowed to paint in oil. Merian painted with watercolours and gouache instead. Research into insects and caterpillars Merian was one of the early naturalists to observe insects directly. Merian collected and observed live insects and created detailed drawings. In her time insects still had a reputation as "beasts of the devil" and the process of metamorphosis was largely unknown. While a handful of scholars had published empirical information on the insect, moth and butterfly life cycle, the widespread contemporary belief was that they were "born of mud" by spontaneous generation. Merian documented evidence to the contrary and described the life cycles of 186 insect species. Merian had started to collect insects as an adolescent and kept a study journal. Aged 13, she raised silkworms and other insects. Her interest turned to moths and butterflies, which she collected and studied. While living in Nuremberg and Frankfurt Merian would travel to the surrounding countryside to search for caterpillar larvae. She recorded their food plants, the timing of their metamorphoses, and noted the behaviour she observed. It was not unusual for naturalists to illustrate their own research, but Merian was among the early professionally trained artists to illustrate her lifelong studies and observations. She observed the life cycles of insects over decades, making detailed drawings based on live insects in their natural environment or freshly preserved specimens. This set her apart from previous artist-naturalists such as Conrad Gesner. Her drawings and engraved plates depict moths laying eggs, or caterpillars feeding on leaves. By drawing live insects Merian could accurately depict colours, which were lost from preserved specimens. The plates she eventually published are complex compositions, based on detailed studies of individual insects she painted on vellum; many are preserved in her study journal. A comparison shows that she changed little and preserved the posture and colour of insects when placing them into the larger composition of her plates. In the course of her insect studies she also recorded and painted the reproductive cycle of flowers, from bud through fruit. As a trained artist Merian was concerned with colour accuracy and in Metamorphosis she recorded the plants from which pigments could be derived. The engravings she produced or supervised are little different from her original watercolours. She also hand-coloured