Dispersal and Oviposition by Navel Orangeworm Moths1

Dispersal and time of oviposition of internally marked (Calco Oil Red N-1700®) navel orangeworm moths were observed in almond orchards by presence of marked eggs on oviposition traps. Positive anemotactic responses were clearly evident when unidirectional air movement predominated. When air movement varied, moths dispersed approximately equal proportions of their progeny at all distances up to 375 meters from the release site. Moth emergence occurred at sunset and was followed by a mating and pre-oviposition period of 24-48 h. Under hot summer temperature conditions, substantial oviposition began about 20 minutes after sunset, continued until midnight and was completed in one or 2 nights. The temperature threshold for oviposition activity was somewhat below 17.9°C, and when this was reached within one h of sunset, oviposition extended over at least 7 nights.