I had my team stand their ground as wave after wave of bugs poured out of that rotting carcass. It seemed like a lot, but I figured it was meant to force me to use every advantage I could find.
I lost count of how many bugs we killed. I don't know how long it took. Maybe an hour? Eventually, new bugs stopped appearing. We got every last one of them, and all my soldiers walked back to the extraction point.
I didn't realize until I found some online comments about that mission that I was supposed to run away as fast as possible when the bugs first appeared.