I came across your interesting website and I wanted to find out if there are any images available for what ant dung looks like.
Thanks for your question! I have to admit, although I've spent a fair amount of time looking at ants, they're usually either dead or foraging: I've never caught one in the act, so this was a fun question for me to try to answer. Luckily, I have access to some other people with lots of ant experience, so I'm able to share their insights.
First, though, let's start with some terminology. When insects eliminate undigested waste, it's called "frass." This is a general term, that also (depending on who you ask) encompases other little particles and exudates that result from insect activities. For example, wood dust that results from carpenter ants gnawing through wood is sometimes considered "frass," even though the carpenter ants don't actually eat the wood - they just cut through it. Since your question is obviously directed towards elimination, we'll focus there.
Something about ants that many people don't realize is that as adults, they are unable to consume big chunks of food. Their jaws are often good at holding and/or cutting through objects, but not well-adapted for chewing food into pieces small enough to swallow. Some ants can eat pollen grains, but solids much bigger than that will not pass through the narrow constrictions at an ant's neck and waist. In a peculiar reversal of the "mamma bird" situation we've all seen on nature shows (and in real life, if you're lucky), adult ants must bring solid foods back to the nest, where the ant babies (larvae) eat it, and then vomit some of the chewed and partially digested food back into the mouths of the adults.
Because adult ants never eat solid foods, their frass tends to be a dark-colored liquid--at least as far as the ants that AntAsk Team members Corrie, James, and Steffi are familiar with are concerned. They (the ants, not the people) also excrete metabolic waste, analogous to urine, in the form of white urate crystals, which James describes as mixing together with the feces in various proportions: "sort of like coffee creamer."
The ant larvae, however, are a different story. They only eliminate waste once during their development, in the form of a dark, compacted mass (can I say "turd" on this blog?) shortly before pupation. This cuts down on diaper changes considerably. Interestingly, albeit disgustingly, sometimes adult ants eat this meconium (reported in Cerapachys biroi by Ravary and Jaisson 2002, and Cephalotes rohweri by Creighton and Nutting 1965). I apologize if you're reading this right before a meal.
As I wrap up this post, I realize I haven't actually pointed you in the direction of any real pictures. There are some pictures of meconia among Alex Wild's excellently curated collection of ant pictures, but I'm not aware of any pictures of an adult ant in the act of defecating. Refuse piles in subterranean ant nests, and below arboreal ant nests are more commonly photographed, but they often contain the bodies of dead workers and discarded prey parts, in addition to frass in the strict sense. So the best I can do is leave you with James' vivid image of a fine white powder mixing into a dark drop of liquid, like creamer into coffee. If I find a good picture of an ant in the act of "frass-ing", I'll let you know!
Hope this helps!
Jesse Czekanski-Moir & the AntAsk Team
ps. if you're interested in other things that come out of ants, please see this previous post about ant pee: