Intelligent alien species based on bugs but specifically those moths that don’t have mouths and only live for a week after they pupate. This species’ whole conscious life is actually in the larval phase; larvae are the ones considered people, larvae are the ones with conscious and complex brains who build society, and each instar of the larva is treated as a different phase of life. Larvae become emotionally and socially and cognitively mature without ever becoming sexually mature. When they pupate, they metamorphose into something different and strange and close to mindless, with no mouth and no digestive system, whose only instincts are to mate and then quickly die. Metamorphosis is treated, functionally, like a person’s death, and the imago phase is a kind of proto-afterlife of majestic flight and the continuation of the species. Birth and death inextricably intertwined. Sex is not something people do during their lives, it’s a thing that is done as an imago after you’ve passed on from your life but before you return to the soil in death. Resultant eggs are collected by family members to raise. I think this would be fun.
You may be interested in a short story in the Predator anthology Eyes of the Demon:
The Distance in their Eyes by Stephen Graham Jones (AND it’s the second story so if you just look at the sample on Kindle the whole story’s included in the first 10%)
I'd also recommend James Tiptree Jr.'s "Love is the Plan the Plan is Death". It's a story told from the perspective of an alien species who have sapience during the warm summer months, but their minds revert to animalistic, instinct behavior ("the Plan") during the cold winter.
