Facebook started testing a way to cross-post Instagram Stories to your Facebook timeline this past September, and finally released the feature to everyone in early October. You can also launch Instagram directly from the Facebook app, making for an even more integrated experience across the two apps. As initially reported by TechCrunch, Facebook is now testing a feature to import and sync your Instagram contacts with Messenger.
As confirmed in an email from an Instagram spokesperson, it's super easy to connect your two accounts, and completely opt-in. Simply launch Facebook Messenger, tap on the People tab and then hit "Connect to Instagram." You'll then tap a button to connect to your Instagram account, which will find all your mutual Messenger contacts from the photo-sharing service. The app will offer the option to start conversations with those people, or you can skip it and just get back into Messenger proper.
Allowing the more than 700 million people who use Instagram (as of last April) easy access to Messenger is a no brainer for Facebook, as it continues to bring it's two hot social properties together on your phone.