stink bugs need help

I found all these stink bugs on my lemon tree.A mate said you must kill then all. I never had any type of stink bug killer so I put on these leather gloves, got a ladder and squashed a heap of them. This is where the trouble started, I took off the glove and my hands had all these stains on them. It doesn't matter what I have tried I cannot make any impression on removing these stains. My hands look like there nicotine stains all over ny palms and fingers. How can I get rid of these? There like brown tatoo's.