Averted: The Chitin are actually sentient trading-partners.
Enforced: Hey! We gotta make our heroes kill dozen of aliens without the audience feeling sorry for any of them. I know! Lets make them giant bugs, because bugs are icky, right?
Lampshaded: "Why is it that every single insect in this galaxy wants to kill us?"
Invoked: The Big Bad lets loose the bugs to help him conquer the planet.
Exploited: Starfish Aliens tricked the Chitin into invading Earth to weaken both sides before they themselves invade. The brutality of the Chitin-Human war means even if the two are able to call a truce and team up against the Starfish Aliens, cooperation is difficult because of harsh memories.
The Chitin are specifically stated as being humanity's greatest ally and friend.
The Chitin are quite docile, even friendly, and produce byproducts humans find useful, and allow humans to harvest these substances on the condition that they help protect the hive if needed and don't cause harm to or interfere with the residents, a'la beekeepers.