Unsurprisingly, the Devourer takes off at a run after its fleeing prey - no need to try to sneak up when it's already been spotted.

Then there's a faint crack overhead, and the pop of displaced matter, and the Intellect Devourer keels over, tumbling with its own momentum, its brainy body skewered by a tree branch.

...And then it rather definitively validates Popp's decision to run for it when its body hisses, convulses, and explodes in a blast of psychic energy.