Diel activity pattern of a nocturnal moth, Zeiraphera canadensis, in nature

Abstract

AbstractThe spruce bud moth, Zeiraphera canadensis Mutt & Free. (Lepidoptera: Tortricidae), displayed a bimodal activity pattern in two young white spruce, Picea glauca (Moench) Voss, plantations. During the day, when temperatures were highest and relative humidities lowest, most moths remained in the lower crown, presumably in response to the risk of hygrothermal stress and/or predation. Flight activity peaks occurred near dawn and dusk. Moths moved higher in the crowns shortly after sunset and many were observed flying above the tree canopy. This activity peak was associated with oviposition and mating. Oviposition started at sunset and continued for approximately 3 h. Females probed oviposition sites with their ovipositor before ovipositing, suggesting that they use sensillae on the ovipositor to evaluate potential oviposition sites. Most mating occurred between 22:00 and 04:00 h. Males hovered adjacent to branches containing females before alighting. After alighting, males usually approached to within 2–5 cm of females and then remained motionless for a short time before attempting mounting, indicating that some short‐range communication usually occurs prior to mating. Reduced flight activity between midnight and dawn was not due to low temperatures, which were above the minimal temperatures for flight for males (10 °C) and females (12 °C) determined in the laboratory.