Insect with a triangular head (6)
I believe the answer is:
mantis
(Other definitions for mantis that I've seen before include "Large-eyed insect, looks as if it's praying" , "Predatory insect" , "Carnivorous insect, which rests as if in prayer" , "A praying . . . . . . is a kind of grasshopper" , "Large insect (sometimes praying?)" .)