Sentence:  By the middle of the summer , many of the <WSD>larvae</WSD> apparently receive such a good diet that it is `` optimal '' , and it is then that young queens begin to appear . 
Meaning of the word marked with <WSD> tags:  the immature free-living form of most invertebrates and amphibians and fish which at hatching from the egg is fundamentally unlike its parent and must metamorphose