A repellent... [He scrubs back his hair in thought and adds with a shrug.] Other than fire, obviously. Right. In order to effectively stop the process I'd have to learn how it works in the first place. So let's take a look at what we know:

We know it takes a number of these bugs to clone anyone. We know they can also clump together an form big-ass monsters. We also know that they require physical contact with a host in order to make a clone. Can you think of anything else importnt?