G. B. Corbin, « Food of wild ducks », Zoologist: a monthly journal of natural history, Londres, Simpkin, Marshall, Hamilton, Kent & Co., 1888, p. 428.
At the beginning of August last, when the shooting season commenced, a friend kindly sent me a couple of full-grown « flappers. » When picked, I noticed how unusually distented the crop of each appeared to be, which, to the touch, was apparently filled with something coarse and rough, like small pieces of chip. Curiosity led me to open them, when I found the whole cavity completely crammed with cases of caddis-worms, some containing the larva and others empty, as if the birds in the eager feeding had indiscriminately swallowed the cases, whether containing worms or, not. I am not versed enough in the Trichoptera to say to what species the cases were referable – probably more than one,- but I was surprised at the quantity the birds had taken at a single meal, and when turned out, it did not seem possible that the two crops could have contained such a mass, especially when we consider the nature of the materialds of which caddis-cases are built, for I should imagine that if the mass had been weighed, the smaller half only would have been digestible, even in the stomach of a duck.but I suppose the wild birds of this family resemble their tame relations in their voracity.