Yep, budwings are pretty fierce, and they don't care if their prey is a roach or a sibling. As for hunting prey, last week I held a medication vial to a flower mantid's feeding port. The mantis got tired of waiting for the fly to emerge and climbed into the vial and took the it there. Ive seen the same thing with bees, which make a loud buzzing noise to make sure that the mantis knows where to find it!
But at least mantids only attack moving prey, right? Wrong. I do not enjoy feeding ffs to individual mantids and encourage them ("yr brother's doing it already!") to take small HFs. Today, I dropped individual stunned HFs into the pots with Joe's tiny L2/3 Rhombodera sp. They were a fair bit smaller than the flies, and the flies were motionless, but still in many cases (8/12) they rushed at the motionless fly, grabbed it and started feeding. Go, nymphs!