Next, the caterpillar must tackle the challenge of the latex. A first instar caterpillar is so tiny this sticky substance can easily immobilize it if it isn't careful. Perhaps you've noticed that the smallest caterpillars will chew a circle into the leaf first, and then eat the center of the ring (see inset photo). This behavior is called "trenching." By doing so, the caterpillar effectively drains the latex from that small area of the leaf, and makes itself a safe meal. The method isn't foolproof, however, and a good number of early instar monarchs become mired in latex and die (according to some research, as many as 30%). Older caterpillars may chew a notch into the leaf stem, causing the leaf to droop and allowing most of the latex to drain out. Once the milky sap stops flowing, the caterpillar consumes the leaf (as in the photo above).