for the attacker ID.

This is a pretty amazing series of photos!! The insect being eaten here is Empicoris sp. (probably E. rubromaculatus). The emesine doing the feeding does not really look like Empicoris to me (in fact I'm not aware of any wingless adults in this genus). But it looks too sclerotized to be and immature emesine. Honestly, I would need to check on this and would maybe need to stick something like this under a scope to know for sure. The Emesinae are very good colonizers in warm climates--the killer in this scene may not be native to North America. I'll try to get some more information on this. It would be best if you would preserve both in 70% ethanol for the posterity of science. And, if you are willing and it comes down to it, I may be interested in your sending it to me for identification.

Furthermore, this intrafamilial predation likely happened because of a lack of desired food sources. They would not likely eat mites and they would be very unlikely to feed on antlions (actually, there is a good chance that the antlion would win that battle). If you had thrown in some adult mosquitoes or fruit flies, they would have satiated their hunger on those.

Moved from True Bugs.