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  1. 254 Female photo by Malcolm Tattersall
  2. 254_0 Female photo by Malcolm Tattersall
  3. 254_1 Male photo by Malcolm Tattersall
  4. 254_2 Male photo by Malcolm Tattersall
  5. 254_3 Male photo by Malcolm Tattersall
  6. 254_4 Male photo by Malcolm Tattersall
  7. 254_5 Male photo by Malcolm Tattersall
  8. 254_6 Male photo by Tony Markham
  9. 254_7 Male photo by Tony Markham
  10. 254_8 Male photo by Tony Markham

Cotton Harlequin Bug

Tectocoris diophthalmus


  • Colour: brightly coloured with a metallic sheen. Baby bugs (nymphs) are a mixture of metallic red, orange, blue and green. Adult females are mainly orange with small patches of metallic blue or green. Adult males are metallic blue, green and red. There are many different patterns among individuals.
  • The top of its body is shaped like a domed shield.
  • Size: 1.5 – 2 cm long (males are smaller than females).


  • Diet: sap from plants in the family Malvaceae, which includes cotton and hibiscus. It pierces the stems of these plants and uses its tube-like mouthparts to suck out the sap.
  • Breeding: after mating, females lay clusters of eggs around stems and stand guard over them until they hatch. They are well known for their maternal care and guard the eggs and young nymphs until they are old enough to fend for themselves and scatter through the foliage.

What to Observe

  • Presence (to establish the first and last sighting for the season)
  • Courting/mating
  • Presence of eggs
  • Presence of nymphs (baby bugs)
  • Mass outbreak

ClimateWatch Science Advisor

Climate change could mean that the distribution of the bug’s food plant changes, which in turn could cause a change in the distribution of bugs. Also, warmer conditions as a result of climate change could result in the life cycle of bugs starting earlier and becoming prolonged. (Ian Endersby, personal communication).

When To Look

  • From summer through autumn.
  • Eggs are laid in early summer.
  • Adults are commonly seen in summer and autumn.

Note: ClimateWatch is looking for any changes in the timing of these events so remember to keep a lookout from late spring!

Where To Look

  • On hibiscus and cotton plants in urban, agricultural and coastal areas.
  • In New South Wales, Queensland and the Northern Territory, particularly along the coast.

Note: ClimateWatch is looking for any changes outside of their known ranges so remember to keep a lookout beyond these regions!

Cotton Harlequin Occurrence Map ALA


The map below displays the accumulated observations of these species as reported by ClimateWatch observers, together with the layer showing how the range of the species might change between now and 2085, with orange areas indicating where the species might disappear, and green areas where the species range might expand.


CSIRO 1991. The Insects of Australia. CSIRO Publishing.

Goode, J 1980.  Insects of Australia. Angus & Robertson Publishers.

Hangay G and German P 2000. Insects of Australia. Reed New Holland, Sydney. 

Schuh RT and Slater JA 1995. True Bugs of the World (Hemiptera: Heteroptera). Cornell University Press, New York, USA.

Zborowski P and Storey P 2003. A Field Guide to Insects of Australia. Reed New Holland Publishers, Australia.

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  1. Did You Know?

    It is sometimes considered a minor pest of cotton plants as it feeds on the young shoots and bolls. It has also been known to cause the introduction of a fungus which rots the cotton boll. It is sometimes a pest on other plants too, such as hibiscus, by sucking the sap out of stems and causing flower buds to drop off.

    It is a member of the Jewel Bug family (Scutelleridae), named for their bright metallic colours which warn potential predators that they smell and taste horrible! 

    There are more than 60,000 known species of bugs worldwide, with many more yet to be discovered. Australia has about 5,650 known species.