Sentence:  He lifted one foot and set it down again, whammo, but Ed was so engrossed in Pynchon's novel that all he recalls is <WSD>tromping</WSD> the scorpion to death with his stung foot, then quickly fetching a bucket of ice water, jamming the foot into it, and continuing to read. 
Meaning of the word marked with <WSD> tags:  To tread heavily, especially to crush underfoot.