The story
Probably from th(io)e(ther) + me(tho)- + -fos (“phosphorous derivative”).
Etymology from Wiktionary, CC BY-SA 4.0.
temefos
Today it means: An organophosphate larvicide used especially to treat water infested with disease-carrying fleas. [O,O,O′,O′-tetramethyl O,O′-sulfanediylbis(1,4-phenylene) diphosphorothioate]. Full definition →