1- How else could = in what other manner is it possible 2- organize highways = used figuratively to refers to the elaborate tunnels that ants build 3-stage epic raids = to collectively attack enemies or prey 4- after all = in spite of situations or expectations to the contrary

1. "How else could" is in reference to the confidence ants have and how they know what needs to be done. Without the confidence and knowledge of what needs to be done they could not do the things listed (organize highways, build elaborate nests etc.) In other words..... without confidence and knowledge what other way would they have to get things done?? 2. Highways is probably metaphorical. Ants march in organized rows similar to how cars drive in lanes on a highway. 3. Not sure about this one. To "stage an epic raid" just means to plan and carry out an attack with the goal of stealing food or houses or other resources from others. I have never known ants to be that aggressive but maybe they are. 4. In this context "after all" is kind of hard to explain. I guess it is just a short way of saying "In spite of how intelligent they appear everything they accomplish is a group effort. They could never do this on their own". Sort of summarizing the sentence.