Women also studied animals that didn't come into the category of companion animals: the correspondence chosen here has to do with barnacles, insects, and worms. (The term ‘insect’ was formerly loosely applied to any small or insignificant animal.) Although they might be collected for aesthetic reasons and studied purely for their own interest, the economic importance of these creatures should not be overlooked. Barnacles slowed down ships, insects destroyed crops, and worms were important to soil fertility. In this arena, female practitioners could be taken seriously: no one could risk doing otherwise, if it sounded as if they knew what they were talking about.

One of Darwin's earliest female correspondents on the subject of zoology (specifically, barnacles), and geology, was Mary Elizabeth Lyell, the wife of the geologist Charles Lyell and daughter of the geologist Leonard Horner. Leonard Horner had taken great care with the education of his daughters; when Mary was 5 years old he noted that she was getting on well in reading, and was learning geography. When she was 13, he was teaching her Italian, and when she was 18 he was congratulating her on her drawing, which she studied formally, and planning to study shells with her. Mary collected land snails on Madeira in 1854. She regularly travelled with her husband and presumably helped him with his work, although the extent of her contribution is unknown. The following letter to her from Darwin of 4 October 1847 suggests that she had her own collection of barnacles.