Everyone knows that a butterfly was once a caterpillar. But what was a ladybug before it was...well, a ladybug? It was a larva, of course—just as that butterfly was. Both of these insects (and more than a million others) are arthropods, a group of animals that have hard external skeletons, segmented bodies, and jointed appendages. Their exoskeletons prevent the manner of growth those of us with internal skeletons experience; in order for insects to grow into sexually mature adults, they need to complete several life stages, a process called metamorphosis. Those that undergo simple metamorphosis start out as nymphs that appear similar to adults, except they are smaller, often have different coloration, and may lack wings. Think grasshoppers and squash bugs: If you've seen the adult insect, you'll also recognize the young. Insects that undergo a complete metamorphosis, on the other hand, are a greater challenge for gardeners to know, because their young, called larvae, look nothing like the adult forms. Consider the Japanese beetle grub, a housefly maggot, or a gypsy moth caterpillar: All change dramatically in appearance when they become adults.
Learning to recognize insects in their larval form can be a big boon to gardeners. It may mean the difference between introducing appropriate pest control and accidentally wiping out a population of beneficial insects. Here are a few common examples of larval insects to get you started.