I've read a lot about crickets biting salamanders (and other herps). What I do is crush all of the legs. My fire salamanders don't grab them quite as quick since they don't move as much, but they are usually gone within a few hours or by the next morning. It's pretty rare that a cricket doesn't move enough to grab their attention at some point. For a pickier eater, you could just remove a portion of the legs to slow them down enough to make them an easy catch and also to make it easier for the salamander to avoid it if needed. I still only leave 1-2 in the tank at a time but I have not had any issues thus far.