Which tick can cause Lyme Disease? Dog fleas?

Deer ticks - Ixodes. Certain ticks are associated with certain diseases. For Lyme disease, classically the 'deer tick' is described- Ixodes scapularis. Deer ticks go through several stages in their life cycle-and the nymphs or younger ones can be extremely small-maybe as big as a pin head. The adults are easier to spot. Dog ticks are larger and are associated with different tick-borne diseases. Good to take precaution.