(With apologies to Jesus Christ) "We know not what we do".

We kill snakes because we think they are poisonous and MAY bite us. (Cars kill over a million people every year, cars are loved --to death). We have "pests and weeds" because we cannot use them for OUR (human) benefits. We kill 100 millions chickens to stop bird flu outbreaks. We kill trillions of mosquitoes to stop malaria and other viral fevers. We will kill more sometimes so that we MAY save one nice fruit. 

Trying to be good practicing Buddhists is not easy. We just can't eat well and speak well...