Science  /  Biography

The Mischievous Morris Sisters

Two gifted sisters in Philadelphia helped to transform early American science.

Margaretta realized that something was amiss in the summer of 1836 when she noticed that her neighbors’ field was not the only one suffering. Newspapers and a few agricultural journals were beginning to report on how Hessian fly larvae were gorging themselves on young wheat plants. Margaretta noted that the fly was appearing around Philadelphia in “appalling numbers” that had not been seen for a generation. The Hessian fly, or Cecidomyia destructor, was capable of devastating wheat yields, creating cascading consequences for farmers and consumers alike in a culture that was so dependent on flour and bread.

At the front lines in the fight to stave off the pests were American farmers, who had been disagreeing about the behavior of these flies and the best methods for protecting their crops for decades. In a primarily rural country, farmers spanned social classes and political parties. They filled pages of local newspapers with descriptions of infestations and tips on how to handle the problem: planting wheat after certain dates or planting certain kinds of wheat, burning stubble, and even seeking out and destroying the countless eggs by hand. Some overwhelmed farmers admitted that nothing they did seemed to help.

Agricultural journals — which supplied farmers with the latest information to support their work — provided a forum to debate how the wheat fly behaved and how they might be able to get a handle on the problem.

These journals had recently begun to publish articles by a few entomologists who specialized in such pests. Some farmers appreciated this, while others balked at the prospect of men, who often lived in cities and were not farmers themselves, presuming to instruct them in ways that countered their own experience and observations.

While some embraced “book farming,” as it was often called, as a way to bring scientific methods into their fields, others mocked it as an unnecessary intrusion. Emotions tended to run high in the pages of these journals when the subject of wheat flies came up, not only because people's experiences across regions differed, but because it invoked a cultural clash between academic expertise and lived experience. So much was at stake, including farmers’ livelihoods, particularly since wheat was the primary grain crop in the United States.