Differentiation by Small Mammal Predators Between Sound and Empty Cocoons of the European Spruce Sawfly

Abstract

In a preliminary paper on the role of small mammals in the natural control of the European spruce sawfly, Gilpinia hercyniae (Htg.), the writer (7) recorded that shrews have a remarkable ability to select sound cocoons in preference to those which are dead or emptied by parasites. This ability was said to be much less apparent, however, in the rodents. However, various experimental aspects of the project on natural control were not completed. This was due mainly to the severe decimation of the sawfly resulting from the combined attacks of small mammals, disease, and parasites. Since the above statements have elicited some interest, it secms worthwhile to present the data on which they were based. Other aspects of the project, particularly those concerned with the populations of small mammals and their relation to forest site, and with the role of larval Elateridae, will be reported later.