These true bugs are a treasure

By Dr Christine Lambkin, Queensland Museum Entomologist

These images show an aggregation of nymphal True Bugs. Not all insects are ‘bugs’ but these are. If you turned one over and looked at the head you might see the proboscis – a long, thin, straight feeding tube lying down between the legs – that makes these ‘True Bugs’ belonging to the Order Hemiptera.

Image credit: Amanda Stevens

Unusually, we can identify these nymphs as they are the commonly seen Hibiscus Harlequin Bug or Cotton Harlequin Bug, Tectocoris diophthalmus, the only member of the genus Tectocoris. These are unusual True Bugs in that the adults look a bit like beetles because part of their thorax, the scutellum, is greatly expanded and covers the entire abdomen. Their two pairs of wings are folded underneath when they are at rest. This feature places Harlequin Bugs into the Family Scutelleridae, Jewel Bugs – a group with unusual but well recorded maternal care. Yes, the mother will sit over the eggs, protecting them from predators and parasites, until they hatch!

Like many insects the different stages and sexes look a little different, but the Hibiscus Harlequin Bug takes this to the extreme. The pattern variation between individuals of this species, and with latitude, is remarkable. In the subtropics, the larger female adults are orange with a few metallic blue patches. The males are red with many more metallic blue patches and the nymphs are the most variable, with every stage looking quite different. In more temperate areas females have larger metallic blue patches and males are mostly blue-green with small red-orange patches.

Like many True Bugs, the Hibiscus Harlequin Bug often form large aggregations, especially while nymphs, as a protective ‘safety in numbers’ strategy. Most of the nymphs in this aggregation are later stage instars with short wing buds, mainly bright metallic blue or green with bright red or orange patches. However, hidden within the cluster are a few very early instars, with dark metallic blue head and thorax and bright red abdomen with dark metallic blue central patch and margin – can you spot them?

Image credit: Amanda Stevens

As you may deduce from their common names – Hibiscus Harlequin Bug and Cotton Harlequin Bug – these bugs suck sap from hibiscus and cotton, and other plants belonging to the Family Malvaceae. They feed mostly from young shoots, and when present in numbers, may cause the plants to wilt. On cotton crops, they are a minor pest, feeding on the valuable bolls as well as the young shoots.

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