Unidentified insect

Unidentified insect

Observation - Unidentified insect. Description: Saw a large group of these insects on grass seedhead along coastpath. Estimate to be about 5mm long. Distinctive yellow abdomen. Interested if anyone knows what they might be.

Saw a large group of these insects on grass seedhead along coastpath. Estimate to be about 5mm long. Distinctive yellow abdomen. Interested if anyone knows what they might be.