Sentence:  Earless ghost swift moths become “invisible” to echolocating bats by forming mating clusters close (less than half a meter) above vegetation and effectively blending into the clutter of echoes that the bat receives from the leaves and <WSD>stems</WSD> around them. 
Meaning of the word marked with <WSD> tags:  A slender supporting member of an individual part of a plant such as a flower or a leaf; also, by analogy, the shaft of a feather.