none. The author investigated the occurrence of sawflies living on spruce in the hills north-west of Nachod in 1989-1990. The sawfly material and their parasitoids were obtained during their eclosion in forest stands under catching frames buried in litter, by sweeps on the ground vegetation cover in the environs of catching frames and by taking litter samples with sawfly cocoons. The method of comparison of feeding types in the sawfly species living on spruce was also used. The author observed the mass outbreak of the sawfly Pikonema montana (Zadd.) in the investigated spruce monocultures (age of mostly 60-90 years) in the period of observation even though the hills are not so high at a relatively low height above sea level, mere 440 m 460 m above sea level. The pest larvae of Pikonema montana caused "bleaching" of needles on spruce branches in the crowns expanding on large areas, often in form of large whitish bands (on sunlit walls of the stands along roads, etc.). The workers of the forest district believed that this phenomenon was due to air pollution emitted from factories and power plants in the vicinity. The litter contained 90% of cocoons of Pikonema montana while the cocoons of a more thermophile hilly species, the sawfly Pikonema scutellata (Htg.), were represented by 12% only out of all the found cocoons of spruce sawflies. Sets of sawfly adults obtained under catching frames during their eclosion confirmed similar dominant percentages of Pikonema montana. In 1989, this dominant percentage accounted for 82% and in 1990 for 62% out of all the spruce sawflies. Eclosion rates of Pikonema scutellata under the frames made only 13% and 27%, resp. These sequences were also confirmed by sawfly counts determined in sweeps. The sweeps contained about 60% of Pikonema montana individuals among all the caught spruce, sawflies in 1990, while the percentage of Pikonema scutellata made 33% only. Two species of ichneumon flies dominated for all methods of catches as for parasitoids: Polyblastus stenocentrus Hlmgr. and Endasys erythrogaster (Grav.). It is apparent that the sawfly Pikonema montana, earlier often taken as a pest causing calamities in mountainous areas, can be responsible for strong gradation or calamity mass outbreak in the Czech Republic, if the climatic conditions are favorable (mesoclimatic) even in not a very high hilly region (about 450 m above sea level), causing great damage.