The enemy that sowed them is the devil
He that is designed by the enemy, who sowed the tares in the field among the wheat, is no other than the devil; the enemy of Christ, of mankind in general, of God's elect in particular, and the accuser of the brethren; and his getting of hypocrites and heretics into churches, is no small proof of his implacable enmity to Christ and his interest; and shows what an adversary he is to the peace, comfort, and fruitfulness of the churches of Christ.
The harvest is the end of the world;
that which is meant by "the harvest", until which time wheat and tares, good and bad men, under a profession of religion, are to be together, is "the end of the world"; meaning either the day of wrath and vengeance upon the Jewish nation; when those that truly believed in Christ were separated from the rest, and that hypocritical generation of men were utterly destroyed; or else the day of judgment, the great and last day, when the heavens and the earth, and all that is therein, shall be burnt up; when the righteous will enter into life, and the wicked go into everlasting punishment:
and the reapers are the angels;
the persons signified by "the reapers", who shall put in the sickle, cut down the tares, bind them in bundles, and cast them into the fire, and who shall gather the wheat into the barn; that is, who shall be the executors of God's wrath, upon wicked professors of religion, and who shall be the means of introducing the saints into the heavenly kingdom, are "the angels"; the holy and elect angels, who are the ministers of Christ, and ministering servants to them, who are the heirs of salvation; and are opposite to all secret and open enemies of Christ and his people; and will be employed in the end of time, against the wicked, and for the righteous.