Questing Behavior of Ixodes pacificus (Acari: Ixodidae) in Relation to Meteorological and Seasonal Factors

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Abstract
The diel questing behavior of adult Ixodes pacificus Cooley and Kohls was examined in relation to meteorological and seasonal factors in outdoor arenas in northern California. Vertical wooden dowels 25, 50, and 75 cm high were provided as potential questing sites. Questing behavior of males and females was positively correlated with relative humidity and negatively correlated with ambient temperature and, to a lesser degree, with light and soil surface temperature. The most frequent questing posture was with the capitulum directed upward. After choosing a questing site, both sexes moved little; most movement occurred nocturnally. Male ticks exposed to direct sunlight stopped questing earlier in the day than those in shade. Questing occurred mainly near the tips of the 25- and 50-cm dowels, averaging 24.7 cm (range, 23.6–25.0 cm; n = 81) and 47.2 cm (25.0–50.0 cm, n = 64), respectively, whereas the mean questing height was not as close to the tip (mean, 54.7 cm; range 27.0–75.0 cm; n = 55) on the 75-cm dowels. Females selected the 25- and 50-cm dowels as questing sites significantly more often than 75-cm dowels. The distribution of ticks of both sexes on 25- and 50-cm dowels was clumped.