Size Growth (object) – The ability to make an object and/or another living being grow larger.
Henry Pym used this power when he was a member of the West Coast Avengers because his body could no longer take the strain of growing and shrinking (West Coast Avengers V1 #21).
There is a very good reason Henry Pym has never tried to take over the world with an army of giant ants (West Coast Avengers V2 #19).
If Henry Pym does get past the above glitch above then he might team up with the following species of intelligent ants that appeared in Uncanny Tales #38.
I did run into an interesting tale of a man who wants to create giant arthropods the old fashioned way (Uncanny Tales #38). Spiders are of course not insects but spiders and insects are both arthropods.
The Silver Age was filled with people getting turned into giants against their will (Action Comics V1 #325, Adventure Comics V1 #308, Adventure Comics V1 #315, Challengers of the Unknown V1 #36, House of Mystery V1 #143, Strange Adventures V1 #28, Strange Adventures V1 #112, Superboy V1 #50, Superman V1 #226, Wonder Woman V1 #136, Superboy V1 #50, Action Comics V1 #325 and Adventure Comics V1 #315, Aquaman V1 #2, Challengers of the Unknown V1 #20 and Challengers of the Unknown V1 #36, Adventure Comics V1 #308, Detective Comics V1 #243, House of Mystery V1 #143, House of Secrets V1 #11, Jimmy Olsen V1 #77, Strange Adventures V1 #112 , Strange Adventures V1 #28, Superman V1 #226, Wonder Woman V1 #136).
Size Lad (DC) can make objects shrink and grow in Adventure Comics V1 #337 (DC).
Muto (DC) uses an expander ray in Action Comics V1 #339.
Zunial (DC) uses a gigantizing ray in Superman V1 #188.
In The Food of the Gods and How It Came to Earth by H.G. Wells, a special food can make animals and humans larger (Classics Illustrated #160).
Tommy Tomorrow (DC) faces a sci-fi version of The Food of the Gods in Action Comics V1 #135.
Jimmy Olsen – “Brainiac…Big Time Operator” – Superman’s Pal #116