Fergusonid galls

Description:

This small eucalyptus tree (1.8 metres) was infested with leaf galls. Various sizes up to 18mm wide. Older ones had many small holes possibly from predatory wasps? On one leaf I found this tiny strange looking fly about 3mm long which looks similar to adult Fergusonid species but not yellow as most seem to be.

Habitat:

In a suburban nature reserve.

Notes:

" The flies have a complex life cycle including the symbiotic association with a nematode of the genus Fergusobia. A fertilised female nematode enters the body cavity of a female fly larva in the gall. The hatched larval nematodes enter the oviduct of the female fly and are carried out of the gall, when the fly emerges. After mating the nematodes are passed out together with the fly eggs, when these are laid into Eucalyptus flower buds. There, the nematodes develop together with the flies inside the induced gall. The chemical that induces the gall is produced by the nematode, therefore the apparently parasitic interaction is of mutualistic nature, hence for the advantage of Fergusonina. Interestingly, a natural enemy of Fergusonina is the gall-forming wasp Megastigmus spp. (Torymidae). Even though being another pest species of Eucalyptus the wasp effectively competes with the fly for suitable flowers to lay eggs, resulting in the death of large numbers of Fergusonina. " - http://www.fzi.uni-freiburg.de/InsectPes...
Further reading starts here...
http://www.pir.sa.gov.au/forestry/forest...
http://it.wikipedia.org/wiki/Fergusonina...
http://nzacfactsheets.landcareresearch.c...
http://bie.ala.org.au/species/Fergusonin...
"Females lay their eggs and nematodes together in the tissues of Eucalyptus and Melaleuca trees (the exact species and location on the plant is dependent on the fly species). Both fly larvae and nematodes develop within the resulting gall together. " - greenzaku
http://greenzaku.deviantart.com/art/Ferg...