They are biege, sometimes appearing transparent with a dark head. Adults - are the size of a sesame seed. Adults are active all winter long, as long as temperatures are above freezing. Adults feed primarily on deer, but will also attack cattle, horses, dogs, etc. Human beings are accidental hosts.
All stages have distinctive features that separate tick species.
Deer ticks do not have festoons. Other common ticks do have festoons. It tends to be in the center of the body of most ticks. On the deer tick, the anal opening is near the lower edge of the abdomen AND is surrounded by a horseshoe-shaped ridge. The risk of being bitten by an infected deer tick is greatest in the summer months, especially in May and June, when the nymph stage is active.