science06:26Why ticks are so hard to killTicks are one pest you don't want to mess with. Once they find a secluded spot on your skin, they use tw...o hook-like structures to tear into your flesh. Then they insert a barbed straw and get to work. If that's not bad enough, ticks also transmit at least 16 different diseases to humans, such as Lyme. And research suggests that several species of ticks — and the diseases they carry — are now spreading in the US.