Prince William and Kate Middleton (opens in new tab) are using their massive platform to promote a good cause.

The couple published an unpublished photo of their daughter, Princess Charlotte (opens in new tab), on the official Instagram account of the Duke and Duchess of Cambridge (opens in new tab) on Saturday morning, along with information encouraging followers to participate in the "Big Butterfly Count". (opens in new tab)

In the stunning photo, Princess Charlotte is wearing a simple periwinkle blue t-shirt and pink floral shorts, holding a Red Admiral butterfly in her hand. This picture is the chicest the world has ever seen of the royal family at her age.

In the caption of the post, Will and Kate (opens in new tab) shared information about the Big Butterfly Count and the important role butterflies play in the environment:

"We are part of the Big #ButterflyCount initiative taking place across the UK, wanted to share these beautiful Peacock Butterflies and Red Admiral Butterflies. Butterflies are an essential part of the ecosystem as pollinators and as a component of the food chain. Hopefully we can top last year's total, @savebutterflies ?"

See for yourself the following photos (including a new snap of Charlotte (open in new tab)):