Seasonal and annual variation in the tick burden on mice.

<p>Average monthly burden of immature <i>Ixodes scapularis</i> ticks (larvae and nymphs) on <i>Peromyscus leucopus</i> mice showed a seasonal pattern over the four years of the study (1999, 2000, 2001, and 2002) for each of the four areas (Control Area, Mallard Road, Nauyaug Point, New Area). Tick burden has units of number of ticks per mouse. There are five sampling months within each year (May, June, July, August, September). The size of the circle is proportional to the number of mice on which the average is based (range: 1 to 64). The properties in the New Area were not sampled in 1999.