I definitely didn't express myself well. What I really mean is: if you're doing scientific experiments with animals, I think they deserve as little pain as possible. I also must say I don't have much sympathy for cockroaches but playing with them like toys while inflicting pain is animal cruelty.
About pest control... well, I don't really care that much about roaches; but I'd do really care if they were, for example, dogs. So, the fact that I don't care that much doesn't means it is not ethically questionable.
If anyone has a good simple idea to develop pesticides which minimize suffering, I wouldn't be opposed to it.