The receiver lima bean plant or maize plant in a pot was infested with 40 adult female T. urticae and 4 third instar M. separata larvae for 24 h. An uninfested potted plant immediately or 1 day after exposure to VOCs served as control. We collected the volatiles from a potted plant in a glass container using 100 mg of Tenax-TA resin (20/35 mesh; GL Science, Japan) packed in a glass tube (3.0 mm i.d., 160 mm length) for 2 h, at a flow rate of 100 ml min21 with clean air. n-Tridecane (0.1 mg) was also added to the glass container as an internal standard. The volatile compounds collected were analyzed by gas chromatography-mass spectrometry (GC-MS) according to the method described in [21]. The headspace volatiles were identified by comparing their mass spectra and retention times to those of authentic compounds, and quantified with calibration curves made using authentic com- pounds. (E)-b-Ocimene was quantified using its authentic compound (SAFC).