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(Phytomyza ilicis).
On hibiscus leaves in the garden
It is most likely to be chromatomyia syngenesiae or chrysanthemum leaf miner, which is common to Australia. See keys.lucidcentral.org/keys/leaf miner/v3/leaf miners/key/Polyphageous%20Agromyzid%20Leafminers/Media/Html
Yes it does look like that Martinl, which is very interesting because we are in the subtropics of Australia. The map shows northern Europe as habitat.
Leaf miners are the larvae of certain flies, wasp, moths or beetles. They mine the soft plant tissue between the upper and lower leaf skin making them hard control. The plant that they are on can be very helpful for ID. However, based on the pattern of damage, I suspect you have the holly leaf miner; Phytomyza ilicis (fly). http://www.discoverlife.org/mp/20q?searc...
...some sort of leaf miner with a purple paint gun ! hope you find out what it is - would like to know. Martinl might be able to help.