Beech leaf disease (BLD) is caused by a microscopic, invasive worm called a nematode that damages the tree’s buds and leaves, and the easiest way to see if a tree has problems is to look for ...

This food chain shows a leaf is eaten by a worm, which is then eaten by a bird. The arrow means 'is eaten by'. A food chain always starts with a producer. This is an organism that makes its own food.