If anyone remembers more details, like the name of the kid that killed the bugs, let me know, and I'll update ;)

His name is Orson and he killed Beetles:

http://pandawhale.com/post/44889/guns-dont-kill-people-george-rr-martin-kills-people-smashing-grrm-also-kills-beetles

The story of Orson and the Beetles is on this page:

http://pandawhale.com/post/44839/game-of-thrones-season-4-episode-8-the-mountain-and-the-viper-gifs-and-memes

And this version of the Beetles is fascinating:

http://pandawhale.com/post/44948/game-of-thrones-s4e8-the-mountain-and-the-viper-analysis-the-beetles-scene-and-the-trial-by-combat-scene-line-up-almost-perfectly