Green-ant mimic

Nearly a year ago I wrote about a bug which was doing a great job of pretending to be a black ant. This time I have one which similarly pretends to be one of our ubiquitous Green-ants. First, the real thing:

green ant
Green-ant – note the jaws

Now here’s the mimic …

green-tailed bug
Not as dangerous as I pretend to be

I noticed it mostly because the antennae looked vaguely wrong for an ant. Looking more and more closely, I could see (1) that the antennae curve smoothly backwards instead of having obvious elbows and pointing forwards, (2) the body is broader and (3) it has no jaws. In fact, it is the juvenile form (nymph) of a sap-sucking bug (Hemiptera), and like all its relatives it has a piercing tube, seen here tucked up against its chest, instead of jaws.

I thought it was a new species to me – I still get them occasionally in my own garden – but through Steve in Airlie Beach I found that I did know the adult but had been baffled by its difference from the nymph. Between us we have a complete sequence showing how it changes as it matures. The one above is the youngest and is the best ant-mimic; as it matures we get …

Green-ant mimic 6626

brown and green bug

ant mimic

Riptortus sp. 2762

The last of these four photos shows the adult, with its wings completely covering its abdomen. The middle two are courtesy of Steven Pearson, and I thank him for permission to use his photos and for identifying my ant mimic. It’s a Pod-sucking Bug, Riptortus sp., Alydidae, Hemiptera.

Riptortus serripes seems the most likely species since it’s the only one I’m sure has been identified in this region, but Brisbane Insects shows its nymphs mimicking black ants. Either we need to look out for another species or Brisbane Insects has confused R. serripes with its smaller cousin Melanacanthus scutellaris.

Green-ant and mealybug

Green-ant tending a lone mealybug on a fern frond
Green-ant tending a lone mealybug on a fern frond

Green ants (Oecophylla smaragdina) are a big feature of life in North Queensland. A lot of people dislike them for the very good reason that they sting but I don’t mind that too much because they are, after all, only defending themselves and they are fascinating to observe. I particularly admire the way they co-operate to make their nests.

They are among the many species of ant which have an amicable relationship with mealybugs. I don’t like mealybugs (Hemiptera, Pseudococcidae) as much as I like the ants, to be honest. Yes, I know mealybugs are only doing their best to survive, just like every other living creature, but they don’t do anything interesting and they do damage the plants they live on.

Yates Problem-solver gives the gardener’s perspective on them:

Mealybugs are small insects covered with a white mealy coating; some have white hairs attached to their bodies. The bugs feed by sucking on the plant juices. Mealybugs excrete a sticky substance called honey dew which ants like to feed on. The honeydew also provides a perfect medium for sooty mould growth. Mild temperatures and high humidity are perfect conditions for mealybugs to breed as eggs hatch every 2-3 weeks. Prolonged hot weather reduces numbers. Heavy infestations can occur on citrus trees, daphne, and other ornamental plants. Orchids and ferns, especially in shadehouses, can also become infested.

There is more on mealybugs’ life cycle and control strategies at About.com and The Spruce.

Queen green-ants

North Queenslanders know green-ants very well. Their nests of woven leaves are common in our trees, and we learn to be cautious about pushing through shrubbery because the workers drop on intruders and bite quite painfully. But there is one stage of the life cycle we rarely see: the winged queen.

Large winged green ant
Winged queen green-ant

Unmated queens-to-be fly from existing colonies in the wet season and, if they are lucky, mate with winged males released at the same time and then establish their own new colonies.

We visited Magnetic Island yesterday and saw dozens of the winged queens. They looked like wasps but were clumsy fliers, often crash-landing into plants or people, and in spite of their powerful jaws they were not at all aggressive.

Green-ant queen
Another, sitting on my finger

The queen, like all flying ants, soon loses her wings. She will find a likely spot for a nest, and start laying eggs, and her children/workers will build the nest around her.

More pics: Worker and Nest construction  on Flickr.

All you ever wanted to know about Green-ants: A masterpiece of evolution – Oecophylla weaver ants by Ross H. CROZIER†, Philip S. NEWEY, Ellen A. SCHLÜNS & Simon K.A. ROBSON, Myrmecological News, 13, 57-71, Vienna, April 2010 (pdf)