TIMING OF IXODES-SCAPULARIS (ACARI, IXODIDAE) OVIPOSITION AND LARVAL ACTIVITY IN SOUTHERN NEW-YORK

Timing of oviposition and larval eclosion for fall- and spring-fed fem ale black-legged tick, Ixodes scapularis Say, and effect of temperatur e on those events in southern New York state, where Lyme disease is en demic, were determined in the field. Mie also examined seasonal patter n of larval host-seeking activity, as well as rate of survival for ove rwintering, unfed larvae. Totals of 9 and 8 replete female I. scapular is were released in fall 1988 and spring 1989, respectively. For the 1 0 females that oviposited, egg laying began in mid-to-late May, regard less of when ticks had fed. Likewise, larval eclosion was synchronized in July for all egg masses. Microhabitat temperatures experienced by females were not reliable indicators of female reproductive success, i n terms of either presence or absence of eggs, or numbers of larvae re covered. However, average body size was significantly greater for fema les that oviposited successfully than for those that did not. The perc entage of unfed larvae surviving the 8-mo overwintering period from la te August to early May ranged from 1.9 to 31.4, with a mean survival r ate of 10.4%. Concurrent drag sampling through the year indicated a bi modal pattern of larval abundance marked by a relatively small early p eak of activity in late May that extended into early July. Because the first peak of larval activity occurred during the period of ovipositi on, 8 wk before onset of larval eclosion, it appears that bimodality r epresents activity of 2 consecutive cohorts, with the early peak compo sed of overwintering survivors. These data imply variation in timing o f reproduction and larval activity from 1 geographic area to another. Efforts to devise a comprehensive scheme for the life cycle of I. scap ularis must consider that population differences may exist.