FIELD ESTIMATES OF NUMBERS OF IXODES-SCAPULARIS (ACARI, IXODIDAE) LARVAE AND NYMPHS PER HECTARE SUCCESSFULLY FEEDING ON PEROMYSCUS-LEUCOPUSIN MASSACHUSETTS

The numbers of blacklegged tick, Ixodes scapularis Say, per hectare th at en gorged as larvae and nymphs on white-footed mice, Peromyscus leu copus (Rafinesque), were estimated at 3 sites in coastal Massachusetts . Estimates of numbers of engorged ticks dropping per day from trapped mice were multiplied by mark-recapture estimates of the density (numb ers per hectare) of white-footed mice to estimate numbers of ticks eng orging on mice per hectare. In 1991, estimates of seasonal totals per hectare of I. scapularis nymphs completing blood meals on P. leucopus ranged from 825 +/- 68 at Nonamesset to 6,654 +/- 770 at Menemsha. Thi s absolute sampling method (the drop-off method) was compared with dra g sampling for nymphal ticks. Per hectare estimation of engorgement ra tes overcomes A shortcoming associated with drag sampling because site -to-site comparisons can be made even where vegetation structure diffe rs markedly among sites. The drop-off method may be used to quantify t he contribution of any host to the engorged tick population, provided sufficient such hosts can be collected on a weekly basis.