Knowing the Enemy: Margaretta Hare Morris and the Birth of Agricultural Entomology.

In the late 18th century, when a crop failed, farmers and agricultural enthusiasts traded theories about what was to be done in the pages of the first agricultural journals, each sticking determinedly to their particular pet explanations and remedies. These agricultural jousts  were a free-for-all where reasonable guesses tumbled against wild conspiracies, and measured responses against fanciful superstition, all carried on without the slightest notion of the worlds of bacteriology or genetics that lay at the root of the problems they were observing. 

While microscopic pests were outside the realm of that era’s imagination, however, the threat that insects held for agriculture would be brought home regularly throughout the 19th century by waves of crop failures caused by hungry larvae and ravenous winged creatures. While most farmers flailed against the onslaughts with their best guesses about what might work, a new generation of scientists was on the rise to bring organized insight into what was attacking their crops, and how they could best protect themselves. This was the first generation who thought of themselves less as collectors of interesting insect specimens, and more as scientists systematically researching the insect world and the life cycles of its constituents. This was the birth of modern entomology.

In the United States, the most prominent figures in early entomology as a practiced science were born in the 1780s and 1790s and included Thomas Say (1787-1834), Thaddeus William Harris (1795-1856), and the individual who put agricultural entomology on the map, Margaretta Hare Morris (1797-1867). While Say and Harris had the advantage of gender in all of their future interactions, Morris had the advantage of family connections. The Morris and Willing families were both prominent and well-established in early Pennsylvania, with relations of means stretched throughout the Republic. When Morris’s father, Luke, passed away in 1802, her mother Ann was able to rely on financial support from her relatives to buy the family a house in Germantown and provide the best of education for her children. 

The benefits of that education fell primarily on Margaretta and her equally talented sister Elizabeth (1795-1865). These were the early days of the new nation, when prominent authors were not only arguing that women should be allowed an education, but that it was a matter of patriotism for all families to provide their daughters with a solid grounding in natural science and mathematics as preparation for their paramount duty of raising scientifically literate young men. Women attended scientific lectures and discussion circles, bought popular science books and subscribed to scientific periodicals, and established schools for girls that boasted a scientific education often more rigorous than that provided in the more classics-oriented boys’ schools. 

Ann did not regularly send Margaretta and Elizabeth to school, but did one better by tapping the rich vein of scientific intellectuals available in nearby Philadelphia as tutors for her children. The sisters learned directly from some of the greatest scientific minds of the nation, including the founder of modern American entomology, Thomas Say, and the naturalists Thomas Nuttall and Charles Lesueur, both of whom boasted international reputations. The sisters then took what they learned and applied it during their rambling hikes along the nearby Wissahickon Creek, where Elizabeth honed her love of plants, and Margaretta her fascination with insects. These rambles deepened both the bond the sisters had for natural exploration, and their bond with each other, which would be the great sustaining fact of their next six decades of shared life together. 

The relative wealth of the Morris family allowed the sisters many freedoms not shared by most women in early 19th century America, perhaps the most significant of which was the freedom from pressure to marry. Unlike most women, for whom marriage was a simple matter of brute financial necessity given the lack of access to most forms of occupation, Margaretta and Elizabeth had enough financial stability from the family’s holdings and their inheritances to be able to simply decline to marry, and instead devote their lives entirely to their own interests and causes. To all appearances, this suited Margaretta fine - though Elizabeth was more drawn to romance and the idea of matrimony, Margaretta was not much given to exploring intimate relationships with the male gender, and was far more engaged by her deep friendships with women like mental asylum reformer Dorothea Dix (1802-1887). 

Without the need to devote time to raising children (though their joint care of their mother would take up an increasing amount of time and energy in the years to come), the Morris sisters were able to explore their scientific curiosities and strike up correspondences with established and rising scientific enthusiasts. Philadelphia was the nation’s scientific capital at that time, and its proximity to Germantown meant that the city’s greatest luminaries were often invited to the Morris household to discuss the latest scientific discoveries and tramp along the Wissahickon with Margaretta or Elizabeth as a guide. Though Margaretta was not considered the equal of her male correspondents, who belonged to prestigious scientific societies she was barred from on account of her gender, they grew to appreciate and respect the rigor of her observations, and when it came time to pit her theories against those of her more established scientific rivals, she would not lack for proponents.

She would soon need them, as a series of disasters befell the wheat crops of Pennsylvania in the 1830s. Wheat had been a key pillar of the state’s agricultural profile since colonial days, when farmers made their money shipping wheat to Barbados to feed the slave population there, and though the 1830s witnessed the start of a turn towards sheep-raising as a crucial source of agricultural diversification, it was still a central crop of the region. The culprit was deemed to be the Hessian fly, or Cecidomyia destructor in Thomas Say’s evocative naming of the insect. Margaretta was fascinated by insects that posed threats to agricultural production, and she set herself the task of rigorously studying the Hessian fly, going to the fields where Say’s original observations had taken place. She found the flies, but not where Say had said they would be. Instead, she discovered them emerging from the head of the wheat. This, then, gave a likely explanation for how the flies were able to return every year - females laid their eggs in the wheat seed, which farmers would store and plant the next year, allowing for a regular cycle of destruction. She believed, in short, that farmers, by using Hessian contaminated seeds, were contributing to their own downfall, and that their best option was to secure seed from non-infected regions to interrupt the cycle.

The Dreaded Hessian Fly

This was sensible advice based on several years of observations of the flies in the wild, and of individuals that she kept and raised in her home. The problem was that these observations contradicted those of Say, the most eminent entomologist on the continent, and the opinions of farmers as expressed in the pages of the nation’s agricultural journals. How could she expect the scientific community to side with a woman against Say, and further expect farmers to take the advice of a lady scientist as against their own experience-based practices? She circulated her ideas privately to friends and other scientists she personally knew, but for four long years resisted all entreaties to make her observations public, until finally in 1840 she allowed her theories were read aloud by her cousin, Robert Hare, at a meeting of the American Philosophical Society.

Thereupon began an all-out war in the agricultural periodicals over the validity of Morris’s observations, with Morris attacked both by other entomologists who had committed themselves in print to extensions of Say’s observations and resolved to discredit her by references to her gender and purported amateur status, and by farmers who found it the height of hauteur for a gentlewoman to lecture them about how to care for their crops. Margaretta, rather than backing down in the face of so much largely gender-based criticism, decided to respond directly to her attackers, compiling more observations, including collecting complete samples of the seed-based fly she had witnessed, concluding at last that this represented a different species than the one Say had somewhat hazily described. The debate lasted seven long years, during which time Margaretta’s repeated need to prove and justify herself pushed her into an ever more public role as a public scientific figure, and gave her the confidence to argue down men attached to the nation’s most venerable educational institutions, secure in the knowledge that her observations were rigorous and her theories sound. 

The experience of sticking to her convictions served her well in the next great controversy in agricultural entomology she would get involved in - the debate over the cicada’s role in the failure of orchard trees. She began investigating this theory towards the end of her battles over the Hessian fly, though her fascination with the seventeen year life cycle of the cicada reached back to her childhood, when she wondered just how it was that the insects maintained themselves for nearly two decades under the ground before emerging en masse. The most common scientific theories of the age held that cicada larvae nourished themselves off of the rich soil nutrients around them, but Morris believed it was something more direct than that. Digging up the roots of the trees that were failing in the family orchard, she noticed that they were covered in what seemed to be two different species of cicada larvae. Looking closer, she saw that they were latched deep into the roots, perhaps drawing nutrients directly from the trees themselves, instead of from the soil. 

A saucy looking cicada

She decided on an experiment, clearing out all of the roots within a circular swath of the infected trees, and filling in the region with new soil. The following year, the trees treated with this method were producing fruit again, and grew new roots which were free of the presence of cicada larvae. Her findings were presented at a December 1846 meeting of the Academy of Natural Sciences (again by a male member of that group - women being blocked from membership), complete with representative specimens. Her experiences with the Hessian fly controversy convinced her that she needed to marshal as much authority on her side as fast as possible, and she invited some of the leading lights in science to observe for themselves the cicada larvae clinging to her roots, including the man who was to become perhaps the most well known scientist in the nation, the Swiss naturalist Louis Agassiz (1807-1873). 

Agassiz was impressed with the thoroughness of Margaretta’s investigations, and when he assumed the presidency of the American Association for the Advancement of Science (founded 1848) in 1850, he used his powers of appointment to nominate both Margaretta and astronomer Maria Mitchell to become the first women members of that organization. Officially, this was the summit of Margaretta’s career, though she continued her natural investigations for another decade, including a discovery that water beetles could carry fish eggs from pond to pond on their sticky legs, an observation that interested Charles Darwin as a mechanism of species propagation, though he ultimately rejected it, not knowing enough about Morris’s observational reliability to include her results in The Origin of Species (1859). 

With the turn of the 1860s, as the United States swallowed itself in the tribulations of the Civil War, the sisters carried on with their nature studies as best they could given the declining state of their health, which often called for travels to new environs as a means of turning the tide on the latest illness. Caring for each other, supporting family, offering guidance to the rising generation of scientists, and contributing to the war effort took time that could have been devoted to scientific pursuits, while the steady urbanization of Germantown took its own toll on the rural surroundings that had proved so rich a field of exploration for the sisters since their youth. In 1865, Elizabeth passed away, and Margaretta would follow her in two years’ time. The jury is still out on her theory about cicada larvae causing long term harm to orchard trees (her discovery of a new species of cicada was validated, but credit for its discovery and naming was taken by other, later, observers), but her results in the case of the wheat flies at the heart of the 1830s crisis, and observation of fish egg propagation through beetles have stood the test of time. We remember Margaretta Morris today for all of this, for her years of contributing as a writer, both anonymous and very much not, to the scientific periodicals of her age, and as an example of a figure from that boundary zone between amateur nature collectors and professional entomologists, who took the advantages of her birth and put them towards the investigation of the world around her, who challenged male centers of authority when they were in the wrong, and devoted her life to studying insects that threatened the well-being of her state and nation, confident in her abilities, and equal to any adversity.

FURTHER READING: One of the great delights in scientific biography of the last half decade is Catherine McNeur’s Mischievous Creatures (2023), a dual biography of Margaretta and Elizabeth. It meticulously brings back to life the Germantown of the early 19th century, and the Philadelphia scientific circles of that age, in prose that is delicious and approachable. It was a delight to read as a purely literary experience, and an important book bringing these two figures the respect that is their due, within the full context of the advantages they had and the institutional struggles they faced. I cannot recommend it enough, to a fan of early botany, to a fan of early entomology, and more generally to anybody with an interest in the complicated world of America’s first attempts to organize its scientific output. An absolute must-have for your Women in Science bookshelves.