T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network


Bug (Swan plant bug) Arocatus rusticus

Kingdom:   Animalia
Family       Lygaeidae
Sub Family         Lygaeinae
Genus        Arocatus
Species      A. rusticus
Binominal name: Arocatus rusticus
Synonym:  A. ruficollis
Common name:  Milkweed Bug. Swan plant bug

Arocatus rusticus is an insect originally from Australia and is now found in NZ, as far south as Central Otago.
It has a body length of 10mm. The adults have the body that orange-red with dull black colours. Head is large and triangular with relatively large raised eyes. Their antennae and legs are black in colour. The front of the thorax red/orange and rear half is a dull black.
The nymphs and adults feed on seeds of swan plant (Asclepias physocarpa), Tweedia (a genus of flowering plants in the Apocynaceae family) and on Parsonsia (Apocynaceae) by sucking their sap.
The Asclepias plants have supposed to have evolved the toxic sap to guard against the plant-eating insects. However it seems that these insects have evolved the mechanisms to overcome the toxin and store it in their own body and have become non-eatable too. Another thing they have done is evolve warning colours to warn-off predators. They can now feed freely on the plants without fear of predators. The adults hibernate amongst dead leaves and under bark.

An adult with wings folded.