To Jonathan N. Havens and Sylvester Dering
Philadelphia Dec. 22. 1791.
I return you thanks for your letter of Nov. 1. with the valuable information it contained on the subject of the Hessian fly. They throw peculiar light on the generations of that insect, which other information had placed under much confusion. If further observations should confirm the fact that there are but two generations a year, it may lead perhaps to a remedy. As the Committee of the Philosophical society will probably continue their enquiries thro’ another year, any further observations which you may make will be thankfully recieved and communicated to them by, Gentlemen Your most obedt. & most humble servt,
RC (PPAP); addressed: “Messrs. Havens & Dering in Shelter island”; franked; endorsed; enclosed in TJ to Ezra L’Hommedieu, 22 Dec. 1791. PrC (DLC).