@ShaulaEvans
I know they aren't insects, but maybe your friend would be interested in the very funky invert that lives round the valley a bit from me. It looks like a caterpillar but is an accomplished ambush predator, shooting out jets of sticky goo to immobilise it's prey. It then injects saliva to dissolve its insides and sucks them out.
Fun fact is that it halted construction of a dual carriageway.