[Guyver Spawn]

Blue Gender is a pretty good show despite the shitty ending that it has. It does have giant bugs in it. It's kinda like Starship Troopers in a Mad Max type of setting it. I remember the bugs in that show where pretty huge though.

Watching Monster Planet did remind me a bit of Blue Gender with a similar post-apocalyptic Earth setting with humans fighting against giant monsters and wanting to take back the Earth from the invasion.