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Sex pheromone-associated behavior of two tortricid moths in New Zealand, Planotortrix notophaea and P. octo , was studied in a laboratory. Most males of both species changed their antennal posture responding to the change from light to dark phase. Three antennal postures in both sexes were designated by dorsal view: antennae in resting position, those extended less than 80° from body axis, and those extended more than 80° from the body axis. In P. notophaea , antennal posture of males appeared as an external indicator representing the physiological readiness for pheromone perception; males with antennae extended more than 80° from the body axis responded better than those in resting position. Bioassays with medicine droppers indicated that threshold concentrations for male response to crude female pheromone extract were 3 × 10 −3 female equivalents (FE) and 3 × 10 −7 FE in P. notophaea and P. octo , respectively. In P. octo , threshold concentrations for male response to known pheromone compounds, (Z)-8-tetradecenyl acetate and tetradecyl acetate, were 10 fg and 100 fg, respectively. Female calling appeared continuous rather than being pulsed. In P. notophaea , stronger male responses were elicited toward females with antennae extended more than 80° from the body axis than those in resting position.

We investigate whether persistent macroeconomic variables can be reliably shown to predict momentum profits. We find that when predictor variables are persistent and the predictive relationship is estimated over a period that overlaps the momentum portfolio formation period, predicted returns will be positively correlated with past returns. This occurs even when returns are constructed to be serially uncorrelated and independent of the predictors. This means there will be a positive predicted return to momentum portfolios and the macroeconomic variables will appear to explain momentum profits, even when stock returns are unrelated to the macroeconomic variables. We show that the apparent ability of the business-cycle model in Chordia and Shivakumar (2002) to explain intermediate-term momentum profits comes from this effect, which we term a relative spurious regression bias. We demonstrate that results similar to those of Chordia and Shivakumar obtain when we replace their macroeconomic variables with random variables constructed to be persistent but independent of stock returns. Once the parameter estimation period is chosen to be prior to the portfolio formation period, the predictive power of the macroeconomic variables disappears and momentum is no longer explained by the business cycle model.