Pea aphid (PA)

Pea aphid, Acyrthosiphon, two adults on stem
Adults showing dark bands around the antennae segments.
Photo: D Ironside
Pea aphid, Acyrthosiphon, adult on stem
Adult showing tube-like projections at the rear of the body.
Photo: D Ironside

General information

In eastern Australia, aphids appear to have declined in pest status since the introduction to Australia of bluegreen aphid (BGA) and spotted alfalfa aphid (SAA) in the 1970s when they caused widespread damage. The decline may be the effect of the development of aphid-resistant pasture cultivars, the build-up of natural enemies and perhaps the seasonal and agronomic conditions.

Scientific name

Acyrthosiphon pisum


Adults are 4 mm long and may be yellow, green or pink. There are dark bands around the antennae segments. They have long siphunculi (tube-like projections on either side at the rear of the body). Adults may have wings. Nymphs are similar but smaller in size.

Similar species

Spotted alfalfa aphid, bluegreen aphid.


Original range included northern Europe, now worldwide. Accidently introduced into Australia, where they are recorded as lucerne pests in all states.

Pest status

Minor, widespread and irregular in damaging numbers.

Crops attacked

Chickpea and lucerne.


Adults and nymphs suck sap causing misshapen leaves, yellowing and stunting. PA can spread bean leafroll virus in chickpeas. It is usually the least abundant of aphids on legume pastures, often occurring in association with BGA.

Risk period

Seedling plants and those in their first year are at most risk of aphid damage.

Life cycle

Females of the species produce live young which grow through wingless nymph stages. Adult males and females may be winged or wingless. All stages may be present in colonies. Winged adults disperse to new hosts. Colony development is dependent on temperature; retarded by cold temperatures and hot summer temperatures.


All crop stages. Frequent monitoring of seedlings and establishing plants is necessary to detect rapid increases of aphid populations. Stem samples give useful estimates of aphid density.

Action level

When damage is apparent, intervention may be necessary. Moderating factors include the degree of aphid tolerance of the cultivar, availability of moisture and the incidence of predators and parasitoids.


Chemical control: Probably effective only for seed crops. For current chemical control options see Pest Genie or APVMA.

Natural enemies: Hoverfly larvae, aphid parasites, green lacewing larvae, brown lacewing, ladybirds.

Conservation of natural enemies: Broad spectrum insecticides should be avoided.

Further information

Last updated 25 October 2010