Why does the Litany of Saint Joseph call him "terror of demons"?

A [litany for Joseph](http://www.ewtn.com/devotionals/litanies/joseph.htm) , the husband of Mary, was approved by Pope St Pius X in 1909 (*). Most of the invocations are straightforward to understand, referring to his life (eg. "husband of the Mother of God", *Dei Genetrice sponse*), virtues ("most faithful", *fidelissime*), and traditional associations/patronage ("model of artisans", *exemplar opificium*). There is one bit which is surprising to me - > Hope of the sick, pray for us. Patron of the dying, pray for us. **Terror of demons**, pray for us. Protector of the Holy Church, pray for us. > > *Spes aegrotantium, ora pro nobis. Patrone morientium, ora pro nobis. **Terror daemonum**, ora pro nobis. Protector sanctae Ecclesiae, ora pro nobis.* I was not aware that St Joseph had anything in particular to do with demons. I can see the part about the sick and dying as an extension of his general image as a protector, especially in relation to the family. Is the demon reference the same sort of thing? Or is there a specific reason - perhaps a traditional story of some kind - why Joseph is called the terror of demons? * *Urbis et orbis: adprobantur litaniae in honorem S. Joseph sponsi B. Mariae V., eisque adnectitur indulgentia*. Sacred Congregation of Rites, 18 March 1909. In *Acta Apostolicae Sedis* 1(6):290-292, 1909. [OCR'd version with some errors](http://www.vatican.va/archive/aas/documents/AAS%2001%20%20-%20ocr.pdf) .