I can’t affirm they are ’cause there are A LOT of hot girls there.
Check out here 31 hot babes (but not just Hot — HOT as hell) I believe they could be the “hottest girls on Instagram”.
Well, I’m not saying they are ’cause this thing of (the) hottest, most beautiful etc. is relative as fuck and there are many girls on Instagram to check each one and “put them into perspective”.
Scroll down and check out the 31 hot Instababes. This is not a “top 10” thing, so there’s no first and there’s no last.