Every year at this time, the flame trees at my girls’ school just erupts in hundreds of Cotton Harlequin Bugs (Tectocoris diopthalmus). The flame trees (Brachychiton sp.) have these fuzzy seed pods, that contain urticating hairs all over them which can cause itching to whoever touches them. The insects are fine with them however, with the nymphs tending to congregate inside the seed pods at times. The mothers of this species lay eggs around a branch, and guards the eggs until they hatch. The young will usually cluster together as a way of defense against predators-powers in numbers when you’re a small stink bug. When disturbed they can emit a foul odor (I think it rather smells like a mild cleaner), which in turn hopefully make the predator think they are inedible.
Over the course of a few weeks, the nymphs will undergo a series of molts (shedding exoskeleton) to grow, and will change colour in the process. The newly hatched nymphs are a bright red, then turning to greens and blues in consecutive molts, and finally settling on a bright orange in adulthood. Males can also be orange and red but tend to have brighter spots of blue and green on them, where the females are just orange with sometimes no spots, and sometimes with very muted coloured spots.
I’ll be doing a follow up post on these, because the other day for the first time, I noticed two separate clusters of nymphs, on different seed pods. They were the same size, but one cluster were the red ones you see above, the other group were all green/blue. I’ve never noticed this before so I’m thinking perhaps the females and males cluster together. And that means the picture of the red ones above would be all female. I can’t find information on this, and up to now have read and assumed all nymphs resembled each other until adulthood. I didn’t have my camera but will be getting a picture soon of the difference.