They Never Metamorphosis They Didn't Like
Enduring drastic changes as you grow might sound like a giant hassle — most of us can barely hack puberty — but it offers its share of benefits.
Most insects undergo major changes in their bodies, biochemical makeup and behavior as they mature. Primitive insects go through a partial metamorphosis in which a few body parts, such as sex organs, mature over time. In such species, juveniles and adults bear some resemblance. Advanced insects, conversely, go through a change so complete that they appear at some stages to be different animals. In the larval stage, their bodies are built to chow down and beef up. Later, they assume an inactive transitional form, or pupa, that tears them down and reshapes them into an adult body built for spreading out and making babies [sources: Meyer, Museum Victoria].
Complete metamorphosis means that juveniles face different predators and don't vie with adults for food. It's a useful way to spread the odds. Perhaps that why, although only nine out of 28 orders go through it, they account for 86 percent of all insect species [sources: Meyer, Museum Victoria].