Evaluation of mass trapping for controlling the spotted tentiform leafminer, Phyllonorycter blancardella (Fabr.) (Lepidoptera: Gracillariidae).

Mass trapping for control of the spotted tentiform leafminer, Phyllonorycter blancardella (Fabr.), was evaluated during 1986 in one experimental orchard near Jordan Station, Ont., and in three commercial orchards in Norfolk County, Ont. Multi-Pher II® traps were used to trap adult males, and Vineland traps were used to monitor adult activity and to obtain a measure of the effect of mass trapping on adult male abundance. In the experimental orchard, Vineland trap catches were similar in the trapped and control plots. In two of the three commercial orchards Vineland trap catches were significantly smaller in the trapped plots during one of the three yearly activity periods. Pre-adult leafminer density was significantly lower in the trapped than in the control plots on three of the seven sample dates in the experimental orchard whereas in the commerical orchards, where up to 91 times as many adult males were trapped per plot per activity period, pre-adult density was significantly lower in the trapped plots only in one orchard on one sample date.