Paper wasps

Paper wasp, Polistes stigma townsvillensis, hanging beneath her new nest.
Paper wasp, Polistes stigma townsvillensis, hanging beneath her new nest.

Paper wasps are common around Townsville, although I don’t remember them from Victoria. They are social insects but not as social as ants or honey bees.

Young adults mate, then each mated female begins her own colony by making a small nest of paper-like chewed up plant material, laying eggs and feeding the larvae on minced caterpillars. When the first generations of larvae (all non-reproductive females) emerge as adults, they join her in building and protecting the nest and in feeding their younger sisters. Males and reproductive females are produced at the end of the season, nests are abandoned and the cycle begins again.

There is a longer description of the life cycle, well illustrated with photos, here on the invaluable Brisbane Insects site. It doesn’t describe our Polistes stigma townsvillensis but the lifestyle is exactly the same except, perhaps, in one respect: it says that the quiet part of the cycle, between emergence of the reproducers and establishment of the new nests is ‘over winter’, which may be true in temperate climates but I don’t think it’s true here in Townsville’s monsoonal climate. My casual observations suggest nest building begins each year during the Wet, especially from January onwards, and that nests reach their maximum size (and are then abandoned) in the later part of the Dry, i.e. August and September. That would coincide pretty well with availability of the caterpillars the larvae are fed upon, but I will look out more carefully for nests later this year to make sure.

Paper wasp with ball of minced caterpillar
Paper wasp with a ball of minced caterpillar she is about to feed to her larvae (as usual, click for larger image)

We have several species, all in the family Polistinae. The most common are Polistes stigma townsvillensis and Ropalidia revolutionalis, smaller and darker; Graeme Cocks pictures them both with more Ropalidia species here. The easiest way to identify them positively is from their nests, which are all differently constructed. A larger nest of  Polistes stigma townsvillensis is here, and nests of Ropalidia gregaria and Ropalidia revolutionalis are here and here respectively. A word of warning: paper wasps are not actively aggressive but they are all perfectly willing to defend their nests and their sting is very painful.

When I was out at Porcupine Gorge recently I saw another brown paper wasp, not quite the same as our P. stigma townsvillensis but so similar that it must be another subspecies of P. stigma.

P.S. I found another different Polistes on Magnetic Island in December 2012 – photos here.

P.P.S. Feb 2013: I photographed a Ropalidia romandi in my garden today. The photo is now here … and I’m now looking out for a nest. It pays to know where they are!

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