A method for trapping Hylobius abietis (L.) with a standardized bait and its potential for forecasting seedling damage.
Pitfall traps with holes at ground level or below ground baited with α-pinene and ethanol alone or in combination or left unbaited were placed in 1-, 2- and 3-yr-old clear-felled areas. The experiment was conducted before the flight period in May, after the flight period in June, and towards the end of the oviposition period in Aug. Seedlings were planted at the beginning of each period. Traps with holes at ground level caught about twice as many weevils as traps with holes below ground. Ethanol and α-pinene combined caught about 6 times more weevils than α-pinene alone, 10 times more than ethanol alone and 25 times more than empty traps. There were no significant differences between α-pinene, ethanol and empty traps. In May and June, population levels were relatively high in all clear-felled areas, and no significant correlations were found between catch and damage, while Aug. showed a strong positive correlation between catch and damage. Possibilities for developing a system for forecasting seedling damage using this trapping method are discussed.