Things could have been different for the Terriers had the resilient Iron not fallen apart half way through the second half.
The loss of the visitor's captain Mark Jackson, who spent some time on loan with the Terriers a couple of seasons ago, through injury didn't seem to disturb their game-plan until much later.
Danny Schofield had initially given Town a 1-0 first half lead against a tough Scunthorpe side after benefitting from the referee's decision to play on after he saw that two players who had clashed heads were OK.
Chris Holland provided the killer pass and Schofield rifled an angled shot past Tom Evans from 8 yards out to open the scoring.
Steve Torpey levelled matters after the break on 63 minutes and Town might have struggled but they quickly restored their lead through Chris Holland and Danny Schofield once again less than a minute later.
Schofield's second goal was a first time hit which sizzled past Tom Evans from a tight angle.
Scunthorpe fell apart after this and, despite an effort by Andy Dawson which tested Martyn Margetson, the Terriers pulled away when Chris Hay made it 3-1 in the 75th minute when he accepted Leon Knight's pull-back and hit a rising shot across Evans.
Andy Booth completed the rout in the 83rd minute when he raced onto Chris Hay's corner, unmarked, and headed home past Evans.
Read Doug Thomson's match report in the Examiner on Wednesday. Let us have your comments on this match - use the comments form on the right of this article or the message board below the stats. icHuddersfield will have the draw for the Area semi-finals on Friday night at 7.50pm.
Town (4-4-2): Margetson, Jenkins, Heary, Gray, Holland, Irons (M. Senior 74), Moses, Baldry (Hay 61), Booth (Macari 87), Knight, Schofield
Subs not used: P. Senior, Dyson
Scorers: Schofield 22, 64; Hay 75; Booth 83
Scunthorpe (4-4-2): Evans, Bradshaw, Dawson, Jackson (Stenton 13), Hodges, Carruthers, Torpey, Calvo-Garcia, McComb, Brough (Sheldon 70 (Quailey 81)), Kell
Subs not used: Barwick, Bennion
Scorer: Torpey 63
Referee: Alan Butler (Sutton in Ashfield)