The parts they leave are just the undigestible ones, like the exoskeleton, making it look like the insect's untouched.
my guess would be to stop the dingoes from eating them
When something is dead, decomposers break down the dead bodies or plants for their food. And when they do they leave some behind.
A slug leaves a shiny trail similar to a snail. This trail can be dangerous to plants, flowers, and crops.
Ants will eat ladybugs, all the ladybugs..while ladybugs are eating afids the ant is eating ladybugs, because the ants somewhat farm the afids for the afids leave droppings that are a food source to ants. So the ant will protect the afids.
Leave them alone. They will hatch out by themselves.
so that they can survive and prey cannot eat .
It would slow it down by an imperceptible amount, and leave a squashed mark on the windscreen (windshield).
Why can't plants and animals not leave what alone? Or do you mean why can humans leave them alone? Because the answer to that question is, "no one knows".
Leave it alone.
Near or on leafy surfaces are where aphids can be obtained. The insect pests in question (Aphidoidea superfamily) leave recognizable accumulations of ant-attracting, sticky honeydew and off-white colorations from draining plants of their internal, life-sustaining saps.
Often insects like bees will leave their group if they are sick and/or dying.
I must leave the horse alone I must leave the horse alone