Recent devclopnlcn tr in the inwt c icidc 1 icld havc rrtnrl~ available tn the economic entomologist a .r\-icle variet, ol rhunlical rompc~urlds which exhibit high toxicity lo ~w t a i n speciru or gl-o~~ps of ~I I F~L I~. ?'he ~)yretlrins, rotenone and nicotine, reinl'orcrtl I,y I l~e tlinin o c o n~l~n u n d~ and thiocyanares of prewar times, have now hccn ioinrd by thc chlol-inatecl aromatic hy~bocarbons: DDT, gammesane, chlordane and tosii llh~nc. IEx~erimentaI Station, Suffield. Alberta. t~o h i n i o n F,nromological Laboratory, Saskatoon, Saskatchewan. THE CANADIAN ENTOMOLOGIST Sept.-Oct. 19471. A miscible oil, having 97% oil, was diluted to a concentration of 4% by mixing 154 ml of the oil with one gallon ot water.