McGlashan took control of the Highlanders First XV clash from the start and led 27-5 at halftime. Five more tries and 29 extra points were added in the second spell.
The other back to shine was first five-eighth Thomas Johnson, who scored two tries and added three conversions and a penalty goal. McGlashan forwards to impress were hooker Matt Morrison and flanker Jordie Ashton.
South Otago High School gained its second successive win when it beat Mt Aspiring College 24-15 in Balclutha.
Mt Aspiring led 15-12 at halftime, but South Otago finished stronger and scored two tries in the last 10 minutes for to win the game.
South Otago scored four tries to get the bonus point but it was hard work because Mt Aspiring played with a lot of structure, with No 8 Elliott Mason having a dominant game.
The best players for South Otago were lock Josh Hill and openside flanker Scott Lawrence.
Midfield back Siua Ngalo scored three of St Kevin's College's 11 tries when Central Southland College was beaten 65-0 in Oamaru. Lock Chris Kearney showed good support play to score two tries, and first five-eighth Brodie Flannery kicked four conversions.
St Kevin's led 34-0 at halftime and never looked in any danger. It maintained possession for long periods and gained quick ball from the rucks.
Otago Boys' High School gained its second win of the season when it scored 13 tries to beat James Hargest High School 81-0 in Invercargill.
Centre Sio Tomkinson scored 29 points with three tries and seven conversions. Fullback Reece Mau'u scored three tries and kicked two conversions. The best forward was No 8 Jamie Mowat.
Other unbeaten teams after two rounds are Southland Boys' High School, which beat Menzies College 60-0, and King's High School, which beat Waitaki Boys' High School 36-30 in the midweek interschool.
St Peter's College beat Dunstan High School 27-14.
