Four, short years ago we announced we were watching the spread of another invasive into the state of Iowa. The European paper wasp, Polistes dominula, was first reported in the US in 1978 near Boston, but it was slow to gain our attention until this decade. In August, 2012 we reported it as relatively new to the state. Now, in July, 2016, it seems to be everywhere and in some areas it is the only wasp seen around the house.
The photo below shows the distinctive characteristic of the elongated body, the yellow-and-back coloration, the folded wings, and most importantly, the orange antennae. No other of the approximately 300 species of related wasps has mostly orange antennae.
European paper wasps are very well adapted to live around human habitations. They prefer to build their open-comb paper nests (see below) in cavities, which, unfortunately, includes holes in foundations, soffits, etc.
Wasp control is best done at night by treating the nest with insecticide. If the nest is in the open, the long-distance wasp and hornet aerosol sprays work well. If the nest is in a cavity we suggest applying an insecticide dust into the nest opening, though a wasp and hornet aerosol spray may work just as well if the nest is near the opening.
There are two disconcerting trends now surfacing with this new invader species:
One. Because of its high rate of reproductive increase, its early start in the spring, a varied diet and the habit of building nests in protected locations, the European paper wasp has competitively displaced native wasp species in some areas.
Two. The European paper wasp is such an efficient and effective hunter and predator of caterpillars in the urban environment that it may be contributing to the decline of butterfly populations. According the Whitney Cranshaw, Colorado State University Entomologist, the European paper wasp "is devastating to essentially all species of yard and garden Lepidoptera." Predation of cabbageworms, hornworms and other pests from urban gardens would be a welcome biological control. However, loss of butterfly caterpillars such as parsleyworms and monarchs is a blow to butterfly gardening. Again, Whitney Cranshaw; " Far too often, I have seen butterfly larvae enticed to develop in my garden get turned into bug burger by Polistes dominula, and I can't take it anymore; breaks my heart."
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