The Sternorrhyncha comprises four main groups of bugs with extreme morphological adaptations:
- Aphids (greenfly and blackfly) are soft-bodied, sap-suckers and are mostly parthenogenetic, meaning that they reproduce without sex.
- Whiteflies are tiny moth-like insects covered by secreted white 'meal', with nymphs that are immobile and thus remain in one spot through their entire pre-adult life.
- Scale insects and mealybugs are members of the Coccoidea. Females are either completely immobile or have limited mobility however whereas males have wings but no feeding mouthparts, meaning they have to mate or die within a short time-frame.
- Jumping plant lice, whose life-cycles are nearer to being 'typical' for Hemiptera in that they have mobile nymphs with well-developed legs and robust adults with four wings.