囊状幼虫

例句：

1. 1.The caterpillars are the larvae of butterflies.
   蝴蝶的毛虫是它们的幼虫。
2. 2. The worm's cyst is a small, hard ball that grows inside its body.
   这条蠕虫的囊状物是一个小而硬的球，生长在它的体内。
3. 3. The cyst was treated with antibiotics to kill the bacteria inside it.
   这个囊状物被抗生素治疗以杀死里面的细菌。