Sternorrhynchan

Sternorrhynchan refers to members of Sternorrhyncha, a suborder of the order Hemiptera, the true bugs. The group comprises several lineages including aphids (Aphidoidea), scale insects (Coccoidea), psyllids (Psylloidea), and whiteflies (Aleyrodoidea). Sternorrhynchans are primarily plant feeders that obtain nutrients from phloem using long, slender piercing-sucking mouthparts. Many have specialized life cycles and morphologies, with winged and wingless forms and, in some lineages such as aphids and other scale insects, complex parthenogenetic reproduction.

Aphids are often parthenogenetic for parts of the year and can give birth to live young. Scale insects include mobile crawlers and sessile adults, often with waxy coverings; their larvae disperse before settling on hosts. Whiteflies and psyllids produce different life stages including eggs, nymphs, and adults, and their mobility and host ranges influence their pest status. The group is cosmopolitan and occupies a wide variety of plant hosts, from ornamentals to crops.

Ecologically, Sternorrhynchans are important as sap feeders and as vectors of plant pathogens; aphids and whiteflies in particular transmit numerous plant viruses. They can cause direct damage through feeding and honeydew production that fosters sooty mold. Economically, they are significant pests in agriculture and horticulture worldwide, often requiring integrated pest management strategies.

The fossil record of Sternorrhyncha extends back to the Mesozoic, with aphid-like forms known from Cretaceous deposits and scale-insect relatives from later periods, illustrating a long coevolution with plants.