The distribution of Sirex equivalents (Sirex adults + parasitoid adults) emerging from trees in the whole data set. The inset shows the distribution of Sirex equivalents among the same number of trees if the Sirex were distributed randomly among trees (a Poisson distribution). The * indicates the mean number of wasps per tree (48.3). The number of wasps along the x-axis is shown in a modified log scale in order to make both small and large numbers of wasps per tree visible.