Some years ago I noted that I had seen yellow paper wasps, Ropalidia romandi, in my garden but hadn’t seen the nest, presumably also in my garden, which they were coming from. It could have been vital information, saving me from a nasty confrontation, so I kept on looking – with no success at all.
I finally spotted it very recently, above the roof-line of our high-set house in a paperbark tree (please visit this page if you want to call it a bottlebrush – it’s both) and overhanging the neighbours’ fence. A clear view of it was only possible from one or two locations even when I knew it was there, so I don’t feel too chagrined at missing it for so long.
It is about the size of a rockmelon, and the telephoto lens shows the wasps moving in and out through well-sheltered openings, as in the larger nest I saw recently at Turtle Rock.
Life cycle and nest construction
Just so that we all know who we’re talking about, here’s one of my older photos of a single wasp:
The nest is made entirely of a papery material consisting of plant fibres glued together with salivary secretions, as this scientific paper explains. Inside the outer envelope of an abandoned nest (do not try looking inside an active nest!) we find a stack of horizontal combs separated and supported by short pillars.
The similarities to bees’ hives are obvious. In fact, Yellow Paper Wasps are more “social” than our other paper wasps, with bigger nests which are able to continue from year to year even in climates unfavourable to year-round activity. A Japanese researcher, J. Kojima, has found that colonies can switch from growth mode (lots of larvae) to maintenance mode (fewer larvae, more stored nectar) according to the availability of food.
Kojima saw this behaviour in colonies on the Atherton Tablelands. It is probably important, too, in SE Queensland (where nests a metre long are reported) but I’m not sure whether it is so necessary here. There’s always more to learn!