Having to go down the rabbit hole of sources to get to the original source is not something that should have to happen.
Also do you know the copyright of the butterfly image? Do you have rights to distribute that image and host it on your article? Do you even know the original photographer? It's highly likely that the blog is plagiarising that image itself. Or they were responsible blog authors and purchased the rights to use the image.
But just because the blog is using it, that does not mean you can use it.
I suggest in the future you source your images that are free of copyrights under Creative Commons CC0. There are websited that catalogue these, however I have found copyrighted images on these "royalty free" websites.
I've just done a search on Flickr.com for images that are allowed to be modified and commercial use. You however must attribute the original author.
https://www.flickr.com/search/?text=butterfly&media=photos&license=4%2C5%2C9%2C10