Beware ! Prof. A. J. Cook, of Agricultural College, Lansing, Mich., announces: "In Bulletin No. 26, issued last week from our Department of Zoology and Entomology, on page 6 a typographical error makes the proper proportion of Paris Green or London Purple to water, for spraying apple trees for the Codling Moth, to be one pound of Paris Green to two gallons of water; whereas the proportion should be one pound of Paris Green or London Purple to two barrels or one hundred gallons of water".