European Paper Wasp

Many readers undoubtedly noticed the sudden dearth of butterflies during the 2015 season. Precipitous declines of larger, more recognizable and beloved species such as Monarchs, Yellow Swallowtails, Black Swallowtails and Mourning Cloaks is alarming. Many blame chemicals, neonicotinoids topping the black list. Certainly many chemical agents are deadly claiming too many innocent victims though in the case of bees, bumblebees in particular, warming habitats due to climate change appear to be a lethal factor. Contrarily, the sudden butterfly population crash in our region is directly traceable to one accidental insect introduction: European Paper Wasp (Polistes dominula).

Many have encountered European Paper Wasp (EPW) presuming them to be extra-large Yellow Jackets (Vespula species). With classic black and yellow striping the assumption is understandable. Much smaller Yellow Jacket, however, nests underground as many have tragically discovered when having inadvertently disturbed a hive during a punishing lawn mowing session. Contrarily, the notorious EPW nests in dry places above ground, often under eaves of buildings or hidden away entirely in walls where protective voids can be filled and crevices invite.

This Old World predator is native to southern Europe, the Mediterranean, north Africa and the Middle East extending its vast range eastward into China. First identified on this side of the Atlantic in Cambridge, Massachusetts, it now extends domain at the time of this writing from Maine down to Virginia and north to Michigan and Wisconsin. It has also now been discovered on the west coast in Washington, California and Colorado. Unknown is how EPW was introduced but a queen stowed away in a dormant state in the crevice of a packing crate would be possible. EPW is outpacing our native Paper Wasp due to several built-in advantages. First, queens differing from native Polistes fuscatus sometimes refurbish previous years' nests rather than build anew thereby establishing colonies sooner. Secondly, its diet is more varied. Third, birds have thus far not recognized it as a food source allowing EPW free license to build safer, larger nests which serve a greater number of hungry individuals. And, fourth, EPW tends to seek out sheltered nesting sites that better insulate from threats. These advantages are allowing EPW to extend its territory at a galloping rate.

EPW exhibits great wariness noticing potential intruders from many feet away. Fortunately for humans it is relatively docile, at least as compared to Yellow Jackets and White-faced Hornets which are notoriously ill-tempered. Unfortunately for butterflies it is lethal.

EPW feeds on soft-bodied insects with one of its preferred foods, caterpillars. Once a caterpillar is discovered communication passes quickly to other members. Hunters descend upon their prey. Commonly the queen herself hunts. The caterpillar is eviscerated by the wasps' mouth parts in a matter of seconds. Often pudgy, vulnerable siblings feeding in close proximity then become targets and an entire family unit is decimated. Once transported back to the hive the queen feeds masticated caterpillar to her larvae.

Fritillary Butterflies had a good year with many about. Jeff Fengler, an entomologist from the New Haven Connecticut Agricultural Station, tells us that it is likely because Fritillaries situate their eggs on leaves near ground level. Young caterpillars tend to feed on the the undersides of these low-level leaves thereby escaping notice and evisceration. But most species feed in upper tiers. Comparatively, these are easily spotted and death is imminent.

Prevention includes awareness of holes and cracks in walls which should be caulked. A broom handle may be employed to disrupt and destroy nests under eaves at dusk, dawn or amid a cold morning when wasps are especially slow or drowsy. A safer strategy is insect sprays designed to disrupt the nervous systems of bees and ants. There are also pesticide powders available. In the case of powders there are canisters appropriate for plunging or pumping. Bulb dusters are also an option. These may better protect from stings, yes: but be aware that these sprays are poisonous concoctions which when handled carelessly are potentially dangerous to humankind and beloved pets. And for those allergic to venom it would be wise to employ a backup strategy that keeps you from potential harm. Always read the label. Protect yourself from inhaling wafting mists or dusts. Keep children and pets away until airborne particulate has dispersed. Apply in the evening or before sunup when the queen is on the nest. Kill the queen and destroy the colony.

Plant butterfly gardens which may help to encourage re-population but please be aware that such a garden planted with the best of intentions may become a killing field. That, my dear readers, is presently an unfortunate and very sad fact. But densely planted gardens may provide enough cover that some beautiful winged wonders will survive and go on to produce another beloved generation. Soon I will spotlight some fine native plants which draw butterflies, bees and many other beneficial insects with the added benefit of rustic beauty. Dig in. Be wary.

penned by Wayne Paquette, December 2015