Distribution and population density of the bushcricket Decticus verrucivorus in a damp-meadow biotope.

A population of Decticus verrucivorus (Orthoptera: Tettigoniidae) was studied in the field over two successive years. The majority of insects accumulate only in certain parts of a diverse habitat. In this area the mean population density of adult Decticus verrucivorus was 3.1/100 m2. Analysis of nearest neighbour distances shows that males have a clumped distribution in the undisturbed habitat. It is concluded that larval distribution reflects the distribution of oviposition sites but that the distribution of adult males, though also depending on the distribution of natural resources and the climatic conditions, is produced mainly by the acoustic interactions with other males. The distribution of adult females does not appear to be determined by the acoustic behaviour of the males. The role of environmental factors such as the availability of food, humidity and temperature, and of the acoustic communication within this species, is discussed with respect to the problem of the high site fidelity of Decticus verrucivorus.