Weevils are evil. They damage crops. That’s a natural evil. So weevildoers are evildoers.
Some weevils are more evil than others. They do more damage.
It’s evil to choose the lesser of two weevils. That makes me complicit in the evil deeds of the evil weevildoers—not to mention the weevil evildoers.
Therefore, if I have a choice between a lesser weevil exterminator and a greater weevil exterminator, it would be morally compromising of me to choose the lesser weevil exterminator over the greater weevil exterminator.
Likewise, unless a pesticide can kill lesser and greater weevils alike, it would me morally compromising of me to use any pesticide whatsoever.
Better to let the evil weevil infestation go unchecked than sully my hands by choosing the lesser of two weevils.