When working with tiny critters, injuries can happen. But you'd be surprised what the most common injury used to be in my breeding tent--before I learned how to prevent it.
Butterflies spend most time clinging to the wall and ceiling of a tent--and most tents have mosquito netting. The mesh cubes used by teachers to hold butterflies have similar material.
Butterflies have two huge claws on each foot--used for clinging to foliage. These claws attach very firmly to netting. When you pull butterflies off netting to transfer or feed them, this can exert s huge force on their legs and claws.
It's astonishing how much force. When I was unaware of the danger, sometimes when I picked up a butterfly, a large object it was clinging to would come along as well.