Payback for all those fleas the Kilrathi kicked off, and for all those roaches you "Raided", and ants you squashed.
*BRILLIANT REVELATION!* THAT'S the bio-weapon we needed to use on them. Drop a bunch of fleas and ticks on Kilrah! Damn, I can't believe it took me almost ten years to come up with that.
They seem to want to experiment with captives. Kinda like you pulling a fly's wings off and then getting kicks watching it try to fly. You brought this all on yourself.
Hey, don't worry, be happy! Start feeding the roaches, let the ants in your pants, and stop stealing the bee's honey and you can avert all the futre nastiness.