MeCH:CHCH:CH(CH2)6CH2SiR1R2R3 [I; R1, R2 = C1-6 alkyl; R3 = C16 alkyl, Ph], useful as pesticides, are prepd. by treating trans,trans-8,10-dodecadien-1-ol (II) with ClSiR1R2R3 at 10-60 Deg in the presence of a proton acceptor. Thus, 18.2 g II, 17.5 mL Me3SiCl and 50 mL Et3N were kept at 25 Deg in Et2O for 15 h to give I (R1-3 = Me) which captured 148 adult male Laspeyresia pomonella over a 78 day period when tested as a sexual pheromone and applied to apple trees in a glue-based dispenser contg. up to 10 mg I. [on SciFinder (R)]