Yellowjackets (Vespula spp. and Dolichovespula spp.), baldfaced hornets (D. maculata), and paper wasps (Polistes spp.) are all considered "wasps" (order Hymenoptera, family Vespidae). "Bees" belong to the hymenopteran family Apidae.
This is the time of the year when wasps expand their nests at an exponential rate which explains the number of e-mails I've gotten recently that have included stinging encounters. A common question has been "where did the nest come from?"
The nests have been with us since the beginning of the season. However, the wasps were flying below our radar owing to small nests containing few individuals.
Wasps spend the winter as fertilized females (queens) in protected locations such as beneath bark, inside hollow trees, etc. As spring temperatures warm, the queens leave their overwintering quarters to find suitable sites for nest construction.
They use their powerful mandibles to grind-up fibers gathered from dead wood and plant stems which they mix with their saliva to extrude water-resistant paper used to construct their nests. This construction technique will be used by their offspring throughout the spring and summer.
Early wasp nests are relatively tiny structures. The elongated nests created by a baldfaced hornet queen may measure no more than 1 1/2" long. She creates help as her offspring complete their development which takes around 20 – 25 days in the Midwest.
This single dominant queen receives even more help once subordinate queens develop. Collectively, they lay more eggs that lead to more workers that lead to larger nests that lead to more eggs … etc., etc. By mid-to-late August, the nests become obvious; sometimes painfully.
However, even the largest wasp nests only last one season. Eventually, the nests give rise to new queens and males (drones). Once the new queens are mated, they fly to their overwintering sites humming Elvis' "I'm Movin' On" leaving the workers behind to their freezing fate possibly humming Bill Withers' “Ain’t No Sunshine.”
Paper Wasps, yellowjackets, and baldfaced Hornets are beneficial insects. These wasps are significant predators because of their need to provide protein to the legless, helpless larvae awaiting food delivery in the nests. The wasp workers forage for caterpillars, sawfly larvae, and other soft-bodied insects from late-spring through the summer. They use their powerful mandibles to grind-up these protein-rich meat items to feed to their larvae so they will develop into new adults.
I once watched yellowjackets decimate a colony of redheaded pine sawflies (Neodiprion lecontei) with the sawfly larvae being carried off one at a time to become meat items for yellowjacket larvae. I've also observed bagworm (Thyridopteryx ephemeraeformis) bags ripped open by baldfaced hornets to extract the caterpillar meat morsels.
Paper wasps, baldfaced hornets, and occasionally yellowjackets also provide the added benefit of serving as plant pollinators. They will visit flowers to feed on energy-rich nectar to support their predatory foraging and wood fiber gathering flights. "Pollinator gardens” (a.k.a. butterfly gardens) are a rich location for photographing these wasps.
Unfortunately, yellowjackets and baldfaced hornets have a deserved reputation for becoming serious late season nuisance pests. Once the drones and new queens complete their development in late summer to early fall, they do not need protein; they need energy from carbohydrates.
The royal newcomers lounge around the nest begging the workers for sweets. To appease these freeloaders, the workers search for foods that provide an energy boost such as soda, donuts, funnel cakes, and adult beverages. There are few things scarier than being chased by drunken belligerent baldfaced hornets decked out in their black leather jackets.
A Final Painful Perspective
Of course, wasps will happily demonstrate their stinging capabilities any time during the growing season. However, understanding why the wasps sting is important to avoiding painful confrontations. They will sting for two reasons: to defend their nests (and young) and to deliver venom to quickly subdue their prey.
Fortunately, despite their belligerent reputations, paper wasps, yellowjackets, and baldfaced hornets are seldom aggressive. What benefit would it be for them to waste energy chasing after people? Unless those people present a clear and present danger to their nests.
Unfortunately, wasp nests may be difficult to see. Obviously, spotting subterranean yellowjacket nests or nests inside walls is problematic. However, I've often been amazed at how effective surrounding foliage can obscure large baldfaced hornet nests.
I've taken pictures in several parks over the years of signs posted near an underground yellowjacket nest alerting the public of the yellow-and-black threat. It's a great solution to a possible stinging problem.
Indeed, the vast majority of painful encounters are associated with poorly planned and executed efforts to wage war on these beneficial insects. Even armed with serious insecticides, we're woefully outclassed because wasps have been defending their nests for tens of thousands of years.
It's best to leave annual wasp nests alone unless the nests are located uncomfortably close to a home, or a family member is highly allergic to their venom. Even then, it may be best for homeowners to seek the help of a professional. Famous last words of a do-it-yourself wasp warrior: "it sprays over 20 feet, but I want to get closer …!"