Sternorrhyncha

Amyot & Audinet-Serville, 1843

plant-parasitic hemipterans

Suborder Guides

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is a suborder of Hemiptera containing aphids, whiteflies, scale insects, and psyllids—groups formerly classified in the obsolete order ''. The name refers to the rearward position of the mouthparts relative to the . All members are obligate plant-feeders with adapted for extracting phloem or xylem sap. Many exhibit highly modified including , , flightless morphs, and eusociality. The group includes numerous economically important agricultural and horticultural pests.

Amphorophora agathonica by (c) Barry Cottam, some rights reserved (CC BY), uploaded by Barry Cottam. Used under a CC-BY license.Aphidoidea by no rights reserved, uploaded by Jesse Rorabaugh. Used under a CC0 license.Aphidoidea by no rights reserved, uploaded by Jesse Rorabaugh. Used under a CC0 license.

Pronunciation

How to pronounce Sternorrhyncha: //stɛrˈnɔrɪŋkə//

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Identification

Distinguished from other Hemiptera suborders by mouthparts originating posteriorly on the (sternorrhynchan condition). Differs from Auchenorrhyncha (leafhoppers, cicadas, treehoppers) which have anteriorly placed mouthparts and generally more active, jumping . Distinguished from Heteroptera (true bugs) by reduced wing venation, often sedentary adult females in Coccoidea, and typically more extreme plant specialization. Psyllidae resemble tiny cicadas with beak-like rostrum; Aphididae have cornicles on ; Coccoidea females often with waxy coverings; Aleyrodidae are small, white, -like in .

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Habitat

All members are associated with vascular plants. Found in virtually all terrestrial supporting vegetation: forests, grasslands, agricultural fields, orchards, urban landscapes, and greenhouses. Many are highly -specific, restricted to particular plant species or ; others are across multiple plant .

Distribution

. Distributed worldwide wherever vascular plants occur. Individual and vary in range from restricted endemics to widespread pests.

Seasonality

Activity patterns vary by group and climate. In temperate regions, many aphids and scale insects overwinter as or stages, with active feeding and in spring through autumn. Psyllids often show distinct seasonal tied to plant . Greenhouse may reproduce year-round.

Diet

All members feed on vascular plant fluids. Most extract phloem sap; some extract xylem. Honeydew is universal, representing processed excess sap. Specific plant associations range from monophagy (single host ) to extreme polyphagy.

Life Cycle

Highly variable across constituent groups. Aphids exhibit complex with parthenogenetic and sexual , often involving alternation between primary and secondary hosts. Scale insects show extreme : females typically , neotenic, and covered with waxy secretions; males are minute, winged, and non-feeding with brief life. Psyllids and whiteflies have more conventional hemimetabolous development but may include multiple generations per year. Many overwinter as or stages.

Behavior

Many are sedentary as , particularly female Coccoidea which remain permanently attached to plants. Aphids and psyllids are more mobile, with some species producing winged morphs. Honeydew production attracts ants, leading to mutualistic associations where ants protect the hemipterans from and . Some aphids and psyllids induce plant galls. Eusociality has evolved in some species.

Ecological Role

Primary consumers in terrestrial , channeling plant productivity to higher . Honeydew production supports diverse of ants, , bees, flies, and other insects. Important prey for including lady beetles, lacewings, syrphid fly larvae, and wasps. Some act as for plant . As pests, they can cause direct damage through feeding, indirect damage via honeydew and , and transmission of plant .

Human Relevance

Contains many of the world's most destructive agricultural pests: aphids (transmission of viral , direct feeding damage), scale insects (citrus, orchard, and ornamental pests), whiteflies (greenhouse and field crop pests), and psyllids ( of citrus greening and other diseases). Management relies heavily on , with numerous successful cases using and predatory beetles. Some scale insects produce commercially valuable products: cochineal (red dye), lac ().

Similar Taxa

  • AuchenorrhynchaFormerly grouped with in ''; distinguished by mouthpart position, more active jumping , and different wing venation
  • HeteropteraOther major Hemiptera suborder; distinguished by different mouthpart structure, typically more visible , and often predatory or habits rather than obligate plant-feeding

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Sources and further reading