i'm livia. let's start with our top story. we're always told that we should enjoy the great outdoors. but as scott reports, we also need to be careful. >> whether it's your backyard or a hiking trail in a national park, you have to beware of the wildlife. [ bear growls ] well, things like bears, mountain lions, gators, and snakes are obvious. i'm talking about a critter that's so small, it's often hard to see. [ woman screams ] yes, i'm talking about ticks. and dr. sheila nolan's an expert. she's from the maria fareri children's hospital at westchester medical center. so, why are ticks trouble? >> so, not all ticks are trouble. certain ticks can carry diseases that they can transmit to people, and those are the ticks that are trouble. >> what sort of diseases can they carry? >> so, that depends on where you live. certain ticks can cause diseases such as lyme disease. another one is rocky mountain spotted fever. and there's lots of other diseases that you see throughout the country. just depends on where you live. >> so, how ca