Lygaeidea & Pyrrhocoroidea

Ant-mimicking Seed Bug I
Ant-mimicking Seed Bug II
Brown Seed Bug
Black and White Seed Bug 

Genus Arocatus - Small Milkweed Bugs

Family Lygaeidae, Lygaeinae

This page contains pictures and information about Small Milkweed Bugs in Genus Arocatus that we found in the Brisbane area, Queensland, Australia. 

Milkweed Bug nymph feeding on seed pod
We commonly call the bugs in this genus Arocatus as Small Milkweed Bugs. They are small to medium in size and can be found on Milkweeds Asclepias sp.. Usually they were found in large number on host plants. Adults and nymphs of different instars stages were found on the same plant. We often found more than one species mixed feeding together. 

Orange Small Milkweed Bug
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Arocatus montanus, body length 10mm
This bug is orange-grey in colour. We found this bug once on 2005 in Yugarapul Park. Please check this page for more information.
Brown Small Milkweed Bug
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Arocatus continctus, body length 7mm
This Small Milkweed Bug has the orange-brown head and with pattern on thorax. Please check this page for more infromation.
Black Small Milkweed Bug
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Arocatus aenescens, body length 7mm
This is the smallest among the five Small Milkweed Bug species we found. The bug has the uniform dark brown colour, except on head the parts near eyes are orange colour. Please click on here for more information. 
Common Small Milkweed Bug, Swan Plant Seed Bug
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Arocatus rusticus, body length 9mm
The Common Small Milkweed Bug adults have the elongated parallel sided body and orange-red with dull black colours. Head is large and triangular. Their antennae and legs are black in colour. They have relatively large eyes on distinct stalks. The thorax is half orange and half dull black. The bugs run quickly along stems and leaves of host plants. More information and pictures can be found here.
Cross Small Milkweed Bug 2
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? Arocatus chiasmus, body length 9mm
This species is very similar to the above species. 
This species is very similar to the Arocatus rusticus. We put a question-mark on the ID of this species because the reference information tell that the A. chiasmus was not found in Brisbane. Anyway, we found them only once. Please check this page for details.

1. Insects of Australia, CSIRO, Division of Entomology, Melbourne University Press, 2nd Edition 1991, pp 499.
2. LYGAEIDAE - Australian Biological Resources Study, Department of the Environment, Water, Heritage and the Arts, 2002.
3. A taxonomic revision of the Lygaeinae of Australia (Heteroptera: Lygaeidae) - Slater, A., University of Kansas science bulletin, v. 52(8,i.e.9) p. 301-481, 1985. 

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Last updated: February 17, 2012.