Ants are heavily sclerotized and have many parts which are very hard, such as their jaws. The parts of ants that are found in the droppings of horned lizards, using Regal Horned Lizard droppings as an example, include pretty much all the ant parts--legs, heads, jaws, thoracic shells. The connecting membranes are gone and the parts are jumbled in the droppings, so digestion probably dissolved the intersegmental membranes. I also note that live Pogos are not very juicy. Hymenopterans can be surprisingly empty of bug juice and still function. I have not read any specific literature on the food value of ants, or how much of their value passes in the droppings of horned lizards, but it seems uncomplicated enough to test some fresh ants for caloric value and compare them to ant parts in horned lizard droppings.

It would also be possible to determine the specific chemical content of ants, and this may have been done already. Edward Wilson might know of some work in this area. Again, comparisons could be made to the chemical content of horned lizard droppings.

This may have all been done already but I have not located any publications dealing with it yet. My thoughts regarding the digestibility of ants stem from my experience with different species of insectivorous reptiles. The ones that eat crickets and other insects seem to produce droppings which are less recognizable as to their contents. I also note that when I fed the occasional ant to my Side-Blotched Lizards and Tree Lizards, I occasionally noticed recognizable ant parts in their droppings.

It may turn out that the reason horned lizard droppings have so much recognizable ant material is an artifact of the way horned lizards feed--by coating an ant with saliva and swallowing it without chewing. Interestingly, crickets and other non-ant prey are chewed a little, though not as much as other kinds of lizards chew the same non-ant prey items.

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