Segment parts of body which appear to be background

Hi, I need to detect and then segment the parts of an insect whose intensities are very close to the background. Could anyone help me in giving some tips in achieving it?Please find the image attached. It has 3 parts, the background, the body and the wing. In this images the wings appear to be overlapping. So, this insect has 2 wings. The image is in RGB and the image I have shown here is the green band.

Threshold works for only few images but not always. I need a robust algorithm for its detection. Does anyone has any idea how to start with it? Please help. Thanks