I have a planned species of aliens that have many commonalities with longhorn crazy ants (cooperation with colonies of the same species, can live in a large variety of environments, and have the ability to have genetic variation with a low number of breeding pairs). They are humanoid bipeds with exoskeletons as well as pseudo-endoskeletons, lungs and hearts to pump blood, and regulate heat by a series of capillaries in their mouths (basically just panting like a dog). Individual physical power, as a whole, isn't that much more than a human.
Socially, their "family" units consist of a female queen, a male drone, and twenty to fifty sexless workers (depending on the sub-species). Its like if an entire tribe operates as a single organism, while all having independent minds. Finally, they have the ability to cooperate with other families to form cities, nations, and empires. After a few millennia of advancement, this species took to space.
My question is: what kind of home-world would this species evolve on? Even with my additions to make them environmental generalists, I got no idea how human-sized insects could exist in the first place. I would love to be able to include details about native cuisine and interesting animals they might take with them to space, but at the moment I'm stumped.