Sentence:  Jerry prepared a glass jar with sterilized sand to act as a nursery for his pulsating <WSD>bot</WSD>, but despite his tender ministrations the larva dried out and died before it could encase itself in a pupal sheath. 
Meaning of the word marked with <WSD> tags:  The larva of a botfly, which infests the skin of various mammals, producing warbles, or the nasal passage of sheep, or the stomach of horses.