Sentence:  The staminate willow catkins , then , provide their visitors with both nectar and pollen ; a marvelous arrangement , for it provides exactly what the bee <WSD>queens</WSD> need to make their beebread , a combination of honey and pollen with which the young of all species are fed . 
Meaning of the word marked with <WSD> tags:  the only fertile female in a colony of social insects such as bees and ants and termites; its function is to lay eggs