What is a good way to locate butterfly in an image
The butterflies are really different and the backgrounds as well, then it makes it really difficult. I would try one of these ideas:


Train the Viola &amp; Jones algorithm on your butterflies. It's a cascade of weak classifiers usually used for face detection (algorithm implemented in all the cameras), but it can be trained for other purposed.
The background seems to be pretty different of the butterflies. I would try to apply the thresholding by histereis according to the values of the pixels on the borders. Like that you select all the similar pixels that touch the border, and it will reduced a lot the region of interest.