What type of cat skin parasite is this?

My cat has about twenty little parasites attatched to him, mainly under his chin and on the front of his chest. They're about 1/2 a mm long and a light sort of greyish-white with reddish legs. They're attatched to his skin like ticks and there's little raised lumps around them. However, I pulled some off and looked at one under a microscope and it only has three pairs of legs, where ticks have four. In all other respects it is like a tick. It is almost perfectly round, slightly elongated, with the three pairs of legs grouped near the front of the body. At the head there is a long mouthpiece/sucky thing and two little antannae looking things, one on either side of the mouth, pointing forward. Please help. He has so many and it will take so long to remove them and i want to know if it is worth it.