Golden Paper Wasp
Polistes aurifer
Observed in the riparian corridor of Florida Canyon, Sta. Rita Mts., Arizona, USA. 27 July 2013. Quercus emoryi. The big wasp is checking an oak gall on Emory Oak for a sugary secretion. Surprisingly a minute wasp called a cynipid is inside the gall.
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Paper wasps are active hunters of insects. To find prey they fly and run over leafy foliage searching for caterpillars, crickets or anything else they can catch. All prey are returned to the nest and fed to the young, wasp larvae. They are also builders of intricate nests of paper to house these growing sisters. The paper is made from cellulose fibers that the wasps scrape from exposed wood. If the nest gets too warm they gather water to cool the nest. All this takes a lot of energy. Sugar is the currency of energy which is what this wasp is getting from the oak gall.
Some galls like this one produce a sugary secretion that attracts many insects. This tree, an Emory Oak, had many such galls and was the focus of much attention by the Bugguide 2013 Excursion because a great number and variety of insects were visiting the galls for the sugar energy. The interactions between the tree, the many insects, the gall maker and no doubt microbes offers a complex story for future ecologists to untangle.