The larva are permanent, which is basically like 4 extra drones each time its used, and on top of that its also helpful if you need extra drones to build structures.

• 要知道幼虫增加就是增加了，不会随时间而消失。基本上每一次使用就相当于4个额外的工蜂。如果你需要额外的工蜂造建筑，它也很有用。