What does “catch” mean? [This means to] come to grips with them, convince, refute them, so that the vineyards of the church may not be spoiled. What else is catching foxes, but overcoming heretics with the authority of the divine law, and so to say binding and tying them up with the cords provided by the testimonies of the Holy Scriptures? [Samson] catches foxes, ties their tails together and attaches firebrands. What’s the meaning of the foxes’ tails tied together? What can the foxes’ tails be but the backsides of the heretics, whose fronts are smooth and deceptive, their backsides bound, that is condemned, and dragging fire behind them, to consume the crops and works of those who yield to their seductions? - "Sermon 364.4"
The foxes who destroy the vineyards are heretics and schismatics who devour with their crooked teeth the blossoming vineyard of the doctrine of Christ, that is, the green minds of the faithful. Would that we not know [such destruction]! - "Commentary on the Songs of Songs 2.2.15"
This animal, which is very shrewd with respect to deceit and craftiness, represents the Jews, Gentiles and heretics, who are always plotting against the church of God, and, as it were, continuously making a racket with their babbling voices. Concerning them the command is given to the guardians of the church: “Catch for us the tiny foxes which are wrecking the vineyards.” - "Commentary on the Acts of the Apostles 19.14"
Foxes. They hurt vines, (Theoc. 5.) and denote false prophets, Ezechiel xiii. 4. (St. Augustine) (Psalm lxxx.)
For. Hebrew, "and our vines of Semadar "ver. 13. (Calmet)
Foxes breed in spring, and greatly infested the country, Judges xv. 4.
It calls these foxes “little” because there are also greater ones. Indeed, the ruling powers of the world are greater at raging than the fallacies of the heretics are at seducing. They are both equally evil, but their respective powers to punish are unequal, for the heretic coaxes to destroy, but the Gentile rages to conquer, the former being peacefully deceptive and the latter being cruel in persecution. But the Lord commands that both receive appropriate dispositions from the keepers of the vineyards, that is, from the leaders of the churches. - "Explanation of the Song of Songs 4.25"
Catch us the little foxes: Christ commands his priests to catch false teachers, by holding forth their fallacy and erroneous doctrine, which like foxes would bite and destroy the vines.
[Those] who spoil the church of God, as the “little foxes do the vineyard,” we exhort you to avoid, lest you lay traps for your own souls. “For he that walks with wise men shall be wise, but he that walks with the foolish shall be known.” - "Constitutions of the Holy Apostles 6.3.18"
