Sentence:  but study this useful little insect, and we find that by care and attention we may not only manage to approach the little <WSD>bristler</WSD>, without fear of its weapon, but extract so many sweets, that when we know its service, we wonder how any one on earth can be so silly as to quarrel with it! 
Meaning of the word marked with <WSD> tags:  Someone or something that bristles.