In an interview with io9, director Neill Blomkamp explains that one of the reasons District 9's aliens find it so difficult to fight back despite their superior technology is that, like some insects, they have a hive mind:
The hive mind [concept] is the most important thing to me, because I love the idea of a civilization that can build all of that technology and then, at the same time, just have a massive population that was just drones that needed direction, and were absolutely incapable of building that stuff on their own. I found that to be a really interesting concept. Also, it sort of explains why they don't turn on the humans. Individually, they may be feeling oppressed, but they don't have it together enough to form a resistance and back one another. So I found that really interesting.
And it's not just their minds that have insect-like attributes. An earlier viral video featured a doctor discussing the peculiar physiology of these creatures.