Ecology of the free living stages of Nematodirus battus.

Eggs of Nematodirus battus placed on grass plots throughout the year were able to develop into infective larvae. In 1973 a large autumn peak was observed as well as the more usual subsequent spring peak. This was attributed to the weather conditions. The ability of the eggs to develop at all seasons is of importance in the survival of the parasite but not in the causation of clinical disease. Eggs washed out of the faeces into the soil develop quicker and suffer less mortality than eggs which remain trapped in the faecal pellets.