Four-horned Gumtree Gall

In photo 3, they are the small bumps to the lower left, on the main part of the gall - reddish looking.

Males (and females) of gall-inducing scale insects need to insert their mouthparts (stylets) into live plant tissue in order to deliver the signals that cause the plant to grow a gall. In most Apiomorpha females and males, the plant tissue needs to be new growth, i.e., young shoots. But galls of females seem to be OK too. You can sometimes see galls of females and males on those of other females - in one of Pam's other photos (https://www.projectnoah.org/spottings/953006005) you can see a small female gall and some young male galls on the gall of an adult female. In some species of Apiomorpha though, like A. munita and A. pharetrata, galls of males are only induced on those of females - they do not induce their own galls on young shoots.

Hmm so the males can sense 'green-ness' but not females. Maybe those males are just on their way out Pam? ie the last ones to go black. So many questions :)

Not necessarily - just needs to be a green gall at the time the young male starts to induce its gall.

Thanks Lyn I have been wondering about that. I presume that would only be on an occupied female gall ?

These are dead galls of males on the gall of a female. In Apiomorpha munita, males induce galls only on galls of females.