love me some Aliens Hives, good luck rest of the universe!

Well that must have been discouraging.

So I'm left feeling somewhat like I've only read half a story. This was the setup, okay, but what does our narrator do with what they've just learned? Succumb to despair we learn in the opening paragraph, but... who're they writing to? What do they hope to have happen? What's the ultimate fate of the diplomatic mission?

Cosmic horror is tricky to write well, because you have to convey a sense of visceral personal terror as well as absolute universal hopelessness. This story leans on the 'absolute universal hopelessness' angle, but leaves it largely at one remove from the narrator. To make what you've written land, I'd suggest you end with the narrator's personal feelings, not only lead with them. (For a example of what this looks like, look no further than the original 'The Call of Cthulhu' short story itself.)

I also can't work out what the actual 'unconventional weapon' is supposed to be. Despair? Psychic visions? Wave after wave of monster bugs?

Now, after all that: the actual writing was clear and read easily, the descriptions were on point, and the mood was good. You clearly have some craft as a writer, and I hope you keep honing it!

That was a nice read and full of atmosphere, as you want to know what it is all about. Nice writing style choosing the perspective of the main character telling the story. Reminds me a bit of the Eisenhorn novels :)

A nice idea and good execution!

I love the Lovecraftian style.

Lovecraftian-type cosmic horror is what it felt like in the opening instantly and nice world-building payoff at the end. 

Not all knowledge is power. :(