#AgHistory; Folks, this post is primarily in response to a question I received from farmer @Metin Ozsavran regarding pre-WWII pesticides. It is something each farmer should be able to discuss at a basic level but is not common knowledge. I assure you misperceptions about pre-WWII pesticides are currently being taught at the collegiate level (the implication in many current textbooks being that pre-WWII methods were safer for people than post-WWII). I ran across these misperceptions myself in two different Ag texts (in my classes) and these will continue to affect Ag policies in the future, since many environmental policy advisors and aides will also have read these same books. I do think you will find it interesting since I previously posted that pesticides date back thousands of years. Fast-forward to the 1800's in the United States and Europe: In the 1860's, the potato beetle was moving westward and decimating crops. During this time, someone began using 'Paris green', an arsenic based chemical used to color paint and textiles. Later, 'London purple' was used (another arsenical compound). A friend who is an expert in traditional textile making had mentioned these compounds were eventually banned in the textile industry after being identified as the cause of several deaths. I have not had time to find the source information on this but have no reason to doubt its veracity. These arsenical compounds were used to combat a variety of chewing insects, and kerosene-soap emulsions for sucking insects during this timeframe.Lead arsenate was used in 1892 to combat the the gypsy moth in New England, leading to powdered lead arsenate for the boll weevil on cotton, leading to calcium arsenate as a more effective version against the boll weevil in 1916. Hydrocyanic acid gas was used on citrus in 1886, and naphthalene on grapes in 1882. As populations grew, the greater intensity of agriculture drew greater pests resulting in heavier applications. Western pears were banned in Boston in 1919 due to excessive residues, and a few years later, Britain would not accept apple shipments from the United States for the same reason. The USDA eventually set up arsenic residue tolerances in 1927, and these were adjusted to lower levels than previously set in 1932 (to 0.01 grains/pound). DDT was invented in 1874 by German chemist Othman Zeidler, and became famous when Swiss chemist Paul Muller discovered its insecticidal value around 1939. I will post more as time and research permits, but the take-away is to always ask 'WHY' civilization adopted certain pesticides, and ensure we do not assume that reverting back to previous methods will somehow result in improvement. The best place to validate the above information (and much more) in one source is the 1962 USDA Agricultural Yearbook celebrating 100 years in agricultural innovation. Will share more as time (and AgFuse number counts) permits.