Aphidomorpha

Definition

An infraorder of sap-feeding hemipteran insects within the order Sternorrhyncha, comprising aphids and their close relatives. Aphidomorpha includes three extant superfamilies—Aphidoidea (true aphids), Adelgoidea (adelgids), and Phylloxeroidea (phylloxerans)—along with several fossil superfamilies of uncertain placement. Members share characteristic piercing-sucking mouthparts adapted for phloem feeding, complex life cycles often involving host alternation and parthenogenesis, and frequently exhibit eusocial tendencies with soldier castes in some lineages.

Etymology

From Greek aphis (aphid) + morphe (form, shape)

Example

The woolly adelgids (Adelgidae: Adelgoidea) that devastate hemlock forests in eastern North America, and the grape phylloxera (Daktulosphaira vitifoliae: Phylloxeroidea) that nearly destroyed European viticulture in the 19th century, both belong to Aphidomorpha alongside the more familiar aphids such as pea aphids (Acyrthosiphon pisum).

Synonyms

• Aphidiformes (obsolete)

Related Terms

• Sternorrhyncha
• Aphidoidea
• Adelgoidea
• Phylloxeroidea
• Coccoidea
• phloem feeding
• Parthenogenesis
• host alternation
• stylet

Usage Notes

Aphidomorpha is sometimes treated as paraphyletic in older literature that excludes adelgids or phylloxerans from the 'aphid' grouping; modern phylogenomics generally supports its monophyly. The infraorder is distinguished from Coccoidea (scale insects) and other Sternorrhyncha by reproductive and morphological synapomorphies, though fossil superfamilies within Aphidomorpha remain difficult to place with confidence. The term is capitalized as a formal taxon name.