I wonder why the flies are on strike. Also our view of animals and how we think of their worth might depend on how we define intelligence. If we think that a cow is an intelligent being then we might think that it's wrong to kill it and eat it. If we think that a cockroach has no intelligence then there's no reason not to kill it. If we believe that all life on the planet has intelligence or what you might consider a soul or a spark of life whatever you want to call it then you might be a verse to killing anything. I'm not sure where you draw the line.