Acta Scientiarum Polonorum
Silvarum Colendarum Ratio et Industria Lignaria

Two methods of autumn search for spruce web-spinning sawflies were compared – the currently employed, performed under the canopy of eight trees in the control plot on crown projection areas of 0.25×0.25 m, and the previous method, in which search was carried out on one crown projection area of 1×1 m. Despite a lack of statistically significant differences between both methods, on average more larvae were found applying the currently used standard method involving 8 pitfall traps. Thanks to a higher number of locations, in which search was performed, the method involving 8 control pitfall traps minimises the risk of considerable errors resulting from a subjective selection of a single search location. It provides greater stability of results and thus facilitates more accurate assessment of the current threat to the stand. Application of this method in forestry practice is fully justified. This study confirmed the need to thoroughly search the soil, particularly around and under stones and at the roots. Larvae tended to gather in these locations. Moreover, it is recommended to search through or even shake out the sod, since in this study many larvae were found within this layer.