Lyme disease is caused by bugs.
The most common sign of infection is an expanding area of redness on the skin , known as erythema migrans , that begins at the site of a tick bite about a week after it has occurred .	tick	tick	erythema migrans	erythema migrans
Ticks are small arachnids , part of the order Parasitiformes .	Parasitiformes	Parasitiformes	order	order (biology)
