European paper wasps (Polistes dominula) have presented a conundrum over the past several years in Ohio. The literature notes these wasps were first found in North America in the 1970s near Boston, MA. They are now found throughout much of the U.S. and parts of Canada.
These highly aggressive colonizers exploded onto the Ohio scene between 2000 and 2010 to become the dominant paper wasp found in our state. They were a frequent topic during our weekly BYGL conference calls with Dave Shetlar and Curtis Young reporting high populations in central and western Ohio and I commonly found them in Greater Cincinnati.
In fact, we had real concerns this non-native would eventually supplant our native wasps including the northern paper wasp,P. fuscatus, and the native wasp,P. annularis. At one point, it became difficult to find these native wasps.
However, the reverse has become true in recent years. I talked with Dave and Curtis to compare notes and we've all observed the same thing. Our native paper wasps have become more common, but the European papers wasps are becoming harder to find. We have no explanation for the apparent reversal of fortune for the European interlopers.
That's why I was so surprised to find the nest that's pictured in the lead image for this Alert in a local park this past Wednesday. In fact, the wasps almost found me! The nest was at eye-level, but I didn't notice them until I was only about a foot away.
My concern was justified. European paper wasps gained a deserved reputation for being very aggressive. This coupled with their propensity to build nests in locations where we generally don't find native paper wasps, such as in dense shrubbery, inside railings and mailboxes, and inside the bases of light poles, frequently brought them into stinging conflicts with people.
However, the European invaders do share several traits with our native paper wasps. Winter is spent as fertilized females in protected locations. The lone over-wintered females start building their paper nests in the spring. They use their powerful mandibles to grind-up fibers gathered from dead wood and plant stems which they mix with their saliva to extrude the water-resistant paper used to construct their nests. They are soon joined by their off-spring including new queens which all join in to gather food and expand the nest. They only use their paper nests for one season and new nest-building is occurring right now.
As with our natives, the European paper wasps are both pollinators and predators. They are frequently found visiting flowers. Look closely at the soon-appearing blooms of bottlebrush buckeye (Aesculus parviflora) and later in the season at the blooms of common goldenrod (Solidago canadensis).
They also gather and grind-up various "meat items" with their powerful mandibles to provide a protein-rich slurry to their helpless grub-like young developing in the paper nest cells. The meat may include caterpillars, sawfly larvae, and other soft-bodied insects which makes them important predators. In fact, some researchers have noted the Europeans may have a wider meat palate compared to our natives which could account for their rapid population expansions at the expense of our natives.
Please Report Your Observations
We would like to gauge the current status of European paper wasps in Ohio as well as elsewhere. However, we need your help.
We would like for you to be on the lookout for these non-natives, but please note that European paper wasps bare a remarkable resemblance to yellowjackets; they are paper wasps wrapped in yellowjacket clothing. In fact, their black and yellow markings caused them to be frequently mistaken for yellowjackets. However, yellowjackets tend to be smaller with shorter legs and more robust bodies. They also construct enclosed paper nests rather than the open nests built by paper wasps.
If you observe European paper wasps, please drop me an e-mail message with the exact location, the situation (nest or wasp), and an estimated number such as "several on a nest" or "lone wasp on flowers." Pictures would be hugely helpful … if you can safely take them!