Frying a caterpillar? (envisages horrific scenes from winky's childhood)
Of course it's not the same, it's far far worse but I think it may be what some normal 7yo boys may do if unchecked and not brought up with enough boundaries, iyswim.
I am sure I read something from ages and ages ago - victorian book I think - which described a gang of bad boys setting fire to a cat. Awful, horrible but possibly natural. I am not saying natural is always OK, we need to teach children not to hurt animals, of course. But, underneath that, we are animals and hunters. Basically, we use and kill animals, most of us - and they suffer. It's just that for most of us, we don't have to think about it.
Yet sometimes even for fun, adults regarded as non-psychopathic and normal go out hunting, torturing and killing animals for fun, because they have a drive to do it. This boy may not have been reined in enough, but this behaviour in itself shouldn't lead us to jump to a label I think.