THE ECOLOGY OF SYMPHYLA PART III. FACTORS CONTROLLING SOIL DISTRIBUTIONS

Symphylids exhibit complex, seasonal, vertical migrations in soil. The effect of soil moisture content, soil temperature, the presence of plants at the soil surface, feeding cycles, moulting cycles, egg‐laying and diurnal rhythms on these migrations were studied. Symphylids migrated in response to changes in soil moisture content and could not survive when soil air was less than 100% R.H. The zone of optimum temperature was 15 to 217° C and survival was limited to the range 27° to 287° C. Food attracted Scutigerella immaculata (Newport) in spite of unfavourable soil conditions, but the animals left the surface soil to moult and lay eggs and during non‐feeding phases. No diurnal rhythms were found. Most favourable conditions for symphylids included soil temperature in the range 15–217° C, moist soil and growing plants at the surface.