Aliens have invaded Colorado. Once again, a non-native species has moved into our territory and established a thriving population. In this case, it’s the European Paper Wasp (left). You can read all about it at the Colorado State University Extension website.
In this case, having this new insect in town is a mixed blessing. Although they look a lot like a yellow-jacket, European Paper Wasps aren’t aggressive; they can sting, but they seldom do. On the down side, they’ve been known to go after the sweet juices of ripe fruit such as cherries, and pose a threat to the orchards on the Western Slope.
On the plus side, they’re voracious predators of many garden pests. The CSU article cited above states, “Most commonly they feed on caterpillars, including the larvae of hornworms, cabbageworms, and tent caterpillars. Sawfly larvae are also commonly taken prey.”
I’m delighted that something is dining on cabbageworms, another invader from Europe. Cabbageworms are the larvae of any of several white butterflies (see photo, left) that hover over broccoli, kale, and other cabbage-related crops, laying eggs that hatch into small green caterpillars. Left uncontrolled, those larvae will quickly reduce a thriving plant to a skeleton.
The bad news is that some caterpillars aren’t problems. They turn into butterflies. Who doesn’t want a bright black and yellow swallowtail adorning their flowers? Many people consider butterflies as indispensible as flowers.
Because these wasps favor urban environments, they’re unlikely to pose a serious threat to the myriad of butterfly species found in the Rockies. However, gardeners around town are noticing the absence of butterflies in their gardens.
While we can’t pick and choose which caterpillars these wasps choose for dinner, we can do a few things to help the butterfly population. (I’ll talk about that next week.) We can also decide whether or not to destroy European Paper Wasp nests on our property. The paper wasps are here to stay, but with a little encouragement from us gardeners, so are our butterflies.
Photos, from top: European Paper Wasp, Small White (from Wikipedia), Western Swallowtail