Kyochuu Rettou
Summary
From tethysdust at MangaHelpers: After an airplane crash during a school trip, Oribe Mutsumi and her classmates were stranded on a seemingly deserted island. Mutsumi found the other survivors, and used her wilderness knowledge to help them. She expects that they will be rescued in about three days, which doesn't seem so long to endure. However, she didn't account for the fact that the island is populated with gigantic killer insects. Her knowledge of butterflies, wasps, and more may be the only thing that will help any of her classmates survive to be rescued!
... and the second season of the Anime did a better job of pacing than I thought they would. I think they moved the Elf village arc from before hostilities with the Principality began to the inter-war period, aka the start of the second season, and used that to pad it out. Good call if that's what they did. In any event. Good season.