Transparency Issues In python

class Insurance(pygame.sprite.Sprite):
    def __init__(self, pos):
        pygame.sprite.Sprite.__init__(self, self.containers)
        self.image = load_image2("insurance1.jpg")
        self._image = self.image
        self.rect = self.image.get_rect(topleft = pos)
        self._rect = Rect(self.rect)
        self.life = 255
        self.killed = False
    def kill(self):
        self.killed = True
    def update(self):
        if self.killed:
            self.life -= 15
            if self.life <= 0:
                pygame.sprite.Sprite.kill(self)
        self.image.set_alpha(self.life)