Unless your friend has asked your opinion, or has asked what the Buddha's teachings are on killing other beings - it may be better to reconsider your intention. We influence others far more by example than by criticism.
---The trouble is that you think you have time---
---Worry is the Interest, paid in advance, on a debt you may never owe---
---It's not what happens to you in life that is important ~ it's what you do with it ---