Rusty Bucket said:
Bombarding won't do anything to them, at all. You'd have to be backing away from them literally forever. The only way you could possibly stop them is if you utterly destroyed every single planet that was vaguely in their path so they can't harvest the biomass from it. That's assuming they're as slow as you say they are, which they aren't.
Which is why any species that engages in space battle with them loses right? Ya....no.
It's already been clearly stated that all tyrannid travel at sub light speed; even slower if you remove their navigational 'narwhal'. They can not do warp jumps. Even the Tau whom are only capable of small hops in the warp would easily be able to outdistance 'any' tyrannid fleet; by at the very least years.(Assuming they were too stupid to simply see them with telescopes when they were decades out.)
As it stands the shadow of the warp extends years ahead of any fleet anyways; meaning the 'loss' of Craftworld Iyanden is ridiculous.(It couldn't escape fast enough?) Rubbish, everyone knows the Eldar are capable of moving their entire craftworlds through the webway.
Obviously Warhammer 40k plot reasoning is sub par, but trying to fake a species which would do horrible in a space scenario, as being a near unstoppable menace, is preposterous.
Ironically if they just gave them warp travel potential then it would resolve the whole issue. At least then they would be able to magically appear on their preys doorstep. But then they actually would be near unstoppable; and the problem goes round.