We discovered many Folsomia candida (Collembola:Isotomidae) living in the nest cell of the larval cicadas Graptopsaltria nigrofuscata located in the cray-like soil below 1m from the ground.

F. candida was found from 46% of the nest cells of cicada while no Collembola were collected from the soil outside the nest cell. Mean depth of nest cells containing F. candida was 61 cm and the maximum depth was 128 cm. Discriminant analysis revealed no significant difference in the nest cell characters with and without F. candida. It appears that F. candida enters into the nest cell located near the soil surface and follows the movement of the larval cicada up to the deep soil where it is impossible for F. candida to reach by itself.

F. candida seems to repeat its life-cycle in an isolated nest cell because of the following reasons, 1) each nest cell is isolated in the soil, 2) the longevity of F. candida was shorter than the larval period of cicada, 3) F. candida can reproduce parthenogenetically, and 4) the body length of F. candida collected in the same nest cell varied greatly.

Multiple regression analysis indicated the number of F. candida was related to the volume of the nest cell, suggesting that the population size in a nest cell is restricted by the volume of the nest cell.