San Jose Scale

Ophelimus spp.

San Jose Scale

profile iconOphelimus maskelli galls on Eucalyptus
by Giancarlo Dessì (CC BY-SA 3.0)
1 of 2
A close up of a tree leaf infested with Ophelimus Eucalyptus gall wasp
profile iconOphelimus maskelli galls on Eucalyptus
by Giancarlo Dessì (CC BY-SA 3.0)
1 of 2
The eucalyptus gall wasp is a tiny fly-like wasp. These wasps belong to a diverse family containing parasitoid wasps, which means they need a living host in order to survive. They are extremely hard to identify, and specimens deteriorate rapidly due to their size, so even some museum specimens still lack identification. The Eucalyptus gall wasp has not long been in the UK. The rash-like galls left by larvae are the best way to identify this species presence.
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Traits

This insect causes multiple pink-brown galls, or raised bumps, to develop on both sides of infested Eucalyptus leaves. It's often confused with oedema, a physiological disorder in plants.

Appearance

These wasps are so small it's unlikely you'd see them. However, they are completely black and are smaller than 1mm. Their presence is best detected from the galls produced by the wasp larvae. Look out for raised swellings on both sides of the leaf. These swellings are around 1mm wide and pink-brown. There will be a tiny grub in each gall. Galling behaviour can cause the leaves to drop from trees- and in most cases, it's at this point infestations are noticed by gardeners.

Symptoms

Leaves covered in raised bumps, or swellings, that are pinky brown. Leaves falling from trees prematurely.

Activity

Diurnal

Personality

Order

Hymenoptera

Family

Eulophidae

Metamorphosis

Complete

Distribution

Parts of Europe, Asia and Africa. Widespread across Australia.

Biological treatment

This wasp will not impact the longterm vigour of trees, but the galls it produces may be unsightly.

Chemical treatment

Insecticides are unlikely to work on this wasp. It's suggested to pick up and destroy any infected leaves which have fallen to the ground and this may help control numbers the following year.

Attracts

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Knowledge and advice

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