These images show a drop of fluid that appears to have been exuded from the moth's "mouth". I realize they don't have "functional mouthparts", but they seem to be able to "hurl".
This series of images were shot over the course of several hours. The first two shots were taken indoors, as I prepared to gently transfer the Cecropia into a cage for transport back to where I found her cocoon last month.
One shot shows her moments before that drop appeared. The next shows her with the drop. The last shot was taken after I set her free (much later--different location). At no time did she seem over stressed, btw.
Curious behaviour!