[Vertical migrations of hungry imagoes of the tick Dermacentor marginatus]

The ticks of D. marginatus display activity at a temperature of 3 to 16 C and relative humidity of 20 to 75%. At a low temperature higher than 19 C their activity is inhibited throughout the whole autumn period at any time of the day. Active appearance of ticks on the stems of vegetation was recorded at 8C and higher in August and the first decade of September (in the morning 16%, in the day time 7.5% and in the evening 74% of ticks become active). As a rule the most high percentage of ticks (56 to 85%) recorded from upper parts of stems was observed in August and first decade of September at evening hours at 12 to 17 C and relative humidity of 50 to 70%.