Pest of the Month for February

Description:

The BGA has four stages of growth
The adults are 3 mm long, slightly smaller than the pea aphid.
They have a waxy, bluish appearance.
Their antennae are uniformly dark in colour.
In the migrating stage, they have one set of wings.

Symptoms:

Blue green aphids are a major pest of lucerne hay crops in spring and autumn. They feed at the plant growing point, sucking plant sap and apparently injecting a toxin.
Damage is observed as reduced growth, shortened internodes, leaf puckering and death of young seedlings.
BGA are occasionaly causing economic damage to lucerne seed crops.

Lady beetles, damsel bugs, lacewings, hoverflies, parasitic wasps and Entomophtora fungus are some of the natural enemies.
Hot summer weather reduces BGA numbers.
Monitor field regularly.
Continue to look for native budworm.
and for green mirids.

Control:

Plant resistant varieties.
The spectrum of beneficial insects can exert significant control over BGA.
An early hay cut can often avert the need for spraying, although this is detrimental to the stand if done regularly.
Strip cutting provides a shelter for beneficial insects, aiding their survival.
Wet, humid weather may spread diseases (Entomopthora so.).
Strategic use of selective aphicide often enables predators to maintain subsequent control over the BGA.
There is no recorded BGA resistance to registered aphicides.

CMS First In Integrated Pest Management