Tick activity skyrockets in the spring (April) when eggs first hatch.  Ticks are most active in late June and early July and slowly become less active in the autumn months.  Ticks are least active and least likely to be feeding in January and February.  While ticks aren't as active in the winter months, it is still a good idea to use tick preventative such as Frontline or Advantix.  Also, do not rule out signs of Lyme disease in the winter months because it can take awhile for symptoms to appear.