They are the only changes to the side crushed 63-15 by New Zealand last Saturday, when the pair came on as replacements, although there are doubts about hooker and captain Keith Wood and No 8 Eric Miller, who were injured in that game.
Maggs, who plays most of his club rugby in the centre, replaces John McWeeney on the left wing, while Erskine comes in at blind-side flanker instead of Eddie Halvey, who is relegated to the replacements. Jan Cunningham takes Maggs' place on the bench.
The Ireland team manager, Pat Whelan, said: "McWeeney was not comfortable in the match, but that does not mean that he is now out of the reckoning.
"He has come a long way in a very short space of time. He just needs a little more time to adjust to the higher levels of the game and he will benefit from the experience of playing for Ireland A against the Canadians next week.
"When it came to the choice between Halvey and Erskine, it was a close call. When Erskine came on as a replacement, he made a bigger impression than Halvey, but Eddie is still very much in the frame."
McWeeney is one of eight full internationals in the Ireland A team to play Canada at Ravenhill in Belfast next Wednesday evening.
The others are full-back Ciaran Clarke, wing Darragh O'Mahony, centre Jonathan Bell, fly-half Paul Burke, prop Peter Clohessy, lock Gabriel Fulcher and flanker David Corkery.
The Saracens scrum-half Brad Free, an Australian who has Irish qualifications, is also included.Reuse content