Gerringong insect expert Michael Hindmarsh was part of the local operation, recently unleashing 60 lantana leafminers on the bush near the Bombo headland.

READ MORE: 30 years of care creates haven at previously-barren Boneyard

Six years ago, farmland near his home in Rose Valley was overrun with lantana, which has a devastating impact on biodiversity.

Leafminer larvae introduced to feed on lantana leaves have done the job.

"Masses of lantana have been savagely chewed up by leafminers, and these mini-mulchers are still on the job in Gerringong," Mr Hindmarsh said.

In mid-April, Mr Hindmarsh used an empty lunchbox to collect as many beetles as he could from Gerringong to transport to Boneyard, joining the bush protection project led by horticulturalist Carl Glaister.

It's prime time for the leafminers, which cause the greatest damage in late summer and autumn, when plants can become defoliated. Mr Hindmarsh says the beetles, about 15mm long, are expected to reproduce at Boneyard and only feed on lantana.

"They are very picky, they just say, 'lantana please,'" Mr Hindmarsh said.

"They will not kill the lantana but the two bushes I initially observed at the Mercure in Gerringong showed a 50 per cent leaf kill thanks to the leafminers.

"At the Boneyard there are walls and walls of immaculate pink lantana. They are a worthy contribution in stressing this weed."

The Bombo Headland Landcare Group is the oldest landcare group in the Illawarra.

The group of volunteers, co-founded by Mr Glaister, carries out monthly working bees to keep the weeds at bay on 40 hectares of land.

"Carl and his group have done a great job, and biological control will be the icing on this cake," Mr Hindmarsh said.