Diurnal change of adult behaviour, daily oviposition and influence of temperature on adult emergence and light trapping data of the beech caterpillar, Quadricalcarifera punctatella (Motsch.) (Lep., Notodontidae)

Ecological properties of Quadricalcarifera punctatella adults needed in population studies were investigated. Diurnal changes of behavior were recorded by video camera. Adults emerged from dusk to midnight (1700–2400) with the peak between 2200–2300. Females copulated the 1st night, though most males began to copulate from the 2nd night. Almost all females began to lay eggs the 2nd night and oviposition continued for several days, with the peak being the 2nd–4th days after emergence. Since females laid several egg‐masses a day, time of oviposition varied greatly from dusk to dawn. Females laid several eggs before flying to a trap because they were not active the 1st night and because most of the trapped females had fewer eggs than the estimated fecundity. Adult emergence lasted for more than 1 month even in the laboratory and there was no difference in emergence curve between males and females. The number of emerged adults in the laboratory and that of adults trapped in the field both fluctuated greatly. Temperature influenced the numbers: many adults were caught on warm nights and only a few on cold nights. This was because high temperatures promoted the emergence and flight activity of the adults. Adults were caught in the field for about 2 months from late May to late July with a peak in mid‐ to late June; more than 75% of the total were caught during this period. Total number of trap catches from 11–30 June was concluded to be a good parameter for comparing annual changes in adult densities in future studies.