Hemiptera Click to enlarge image
Psyllid (Order Hemiptera, suborder Sternorrhyncha) Image: Andrew Howells
© Australian Museum

Psyllids, along with aphids, scale insects and whiteflies, belong to the Order Hemiptera, suborder Sternorrhyncha.

What do psyllids look like?


  • 1 mm - 40 mm in length.


  • Psyllids, whiteflies and male scale insects are generally widest at the wing attachment (wide shoulders), abdomen tapered or globular.
  • Aphids are blob-like.
  • Mealybugs look like a dome with segments.
  • Lerp insects (immature psyllids) and female scale insects are larvae-like but their waxy coating can come in a wide range of shapes.


  • Thread-like, length variable.


  • Large and widely separated.
  • Often absent in scale insects and other non-moving species.


  • For piercing and sucking, do not have visible palps (look like a chain of beads).
  • Very small tube, thorn-like in appearance and appearing to come from chest.
  • A small number of species have reduced mouthparts that maybe difficult to see, or retractable tubular mouthparts that are hidden in the head when not in use.


  • One or two pairs if present.
  • Male scale insects have membranous forewings with only one or two veins, hindwing absent or greatly reduced.
  • Both pairs of whitefly wings are membranous, clear or partially see-through with one or two veins.
  • Both pairs of psyllid wings are membranous, often covered with white waxy scales.
  • At rest, wings are held tent-like over body for all groups.


  • Six legs short and stocky.
  • Some female scale insects lack legs.

Abdomen tip:

  • Cerci (tails) absent.
  • Male scale insects may have a single spike or waxy filaments.

Where are psyllids, aphids, scale insects and whiteflies found?

  • On the leaves or young stems of plants.
  • In ant nests.
  • In galls, which they create.

What do psyllids, aphids, scale insects and whiteflies do?

  • Some are solitary but most form groups around a common food source.
  • When disturbed they jump, run away, remain still or emit an chemical informing others of danger.
  • Most lerp and female scale insects are fixed to a plant surface. They hide themselves under waxy or sugary secretions, which harden and form a protective shield. These shields are highly variable in shape, with dome-like to scallop-like shells.
  • They are primarily sap feeders.
  • Many, especially aphids and mealybugs, are tended by ants, which drink the honeydew they exude.
  • Some produce eggs but some such as aphids produce live young. Some do not mate and produce only female offspring.
  • They are active during the day or night.

What looks similar?

  • Psocids are easily confused with psyllids. Psocids maybe distinguished by their large bulging nose, long antennae, wing veins that form 'S-shaped' lines, long slender legs and they usually run or fly away when disturbed rather than jump.
  • Flies can be confused with male scale insects as they both have only one pair of functional wings and another pair that are reduced to haltere-like structures. However, male scale insects have only two or three veins in their wings, the haltere-like structures are not club-like and they often have a tail of waxy filaments. Flies never have this combination of characters.