Studies on the larval activity of the tick Ixodes ricinus L. in Co. Wicklow, Ireland.

The activity of larval I. ricinus was studied in the field and on experimental plots in an attempt to determine the origin and population dynamics of larvae at different times of the year. A comparison of sampling methods showed that the previously observed small size of the spring peak relative to the midsummer peak is not a sampling artifact and is a genuine measure of the prevalence of active larvae. It was established that spring-active larvae are derived from spring-fed adults which contribute comparatively few larvae to the midsummer peak. The small size of the spring peak is probably due to relatively poor activation and survival of available larvae at this time. A distinct emergence and activation of larvae, almost certainly derived from autumn-fed adults, was detected in July, which is before the diapause period. Such larvae would be capable of producing spring nymphs and this is probably a major means of transfer of ticks between spring and autumn populations.