Let's be honest, keeping beetles in their larval stage is completely useless despite they spend in this stage 1/3 of their lives. Seriously, they just take the place and eat your resources like parasites. So I thought: what if there was something that could make this stage more useful?
As we know, larvae are hungry creatures. They gain weight and store energy for successful transformation into an adult insect. I came up with a special "weight bar" (not sure how else to name it), similar to the cub training bar, that will depend of feeding. Every time you feed your larva, it will gain some weight. It's not nesessary to feed your larva every day (as any herb boosts its hunger bar to 0). At the end, when a larva ages into an adult, it gains some exp and/or stats, depending of weight it has gained.