Autumn is Approaching – Watch for Wasps!

Debby Luquette
Adams County Master Gardener

(10/5) The temperatures are getting cooler and the days are getting shorter. Fall is beginning to make its presence known. In the vegetable garden, the tomatoes are looking tired and the zucchini has about given up. The wind is rattling the corn, and the pumpkins and winter squash are ripening. Vegetables planted for the fall – lettuce, spinach, carrots, beets, etc. – are reveling in the cooler weather.

In the pollinator garden, the change in seasons is heralded by the New England aster’s bright purple and the goldenrod’s brilliant yellow. Even as the coneflower and mountain mint have given up early under this summer’s brutal heat and drought, there are still flowering plants offering nectar and pollen to a variety of bees, beetles, flies, butterflies – and wasps! Since I’ve taken more interest in the insect activity associated with gardening, I’ve spent more time noticing how insect activity changes with the season, too.

I read in the Times earlier this month, that with this summer’s heat and drought, yellow jackets were more numerous and aggressive this year. Friends who unexpectantly encountered them have also attested to this fact, especially after mowing over an active nest. At the same time, I encounter bees and wasps of all sorts in the garden, including yellow jackets, and haven’t been stung once. Am I just lucky?

After my husband’s third mowing encounter with an unseen yellow jackets’ nest this year, he asked what their ecological role is. I want to make the point that wasps, despite their bad reputation, are fascinating and ecologically important. If we take some time to understand these creatures, learn something about their behavior and lifestyle, we can safely coexist with them.

Yellow jackets, paper wasps, and white-faced hornets – all social bees and wasps – need to defend their nest. Since they live in colonies which support many offspring, they make a good target for an insect-eating animal. Skunks and racoons can dig out and destroy the nests during the night when the insects are inactive. In fact, skunks have always been our reliable yellow jacket removal service until we moved to Adams County. (Our yard is good skunk and racoon habitat, but for some reason, the ones we encountered when we first moved here have disappeared!) That said, I wouldn’t try to remove a wasps’ nest myself, even at night. Should you want to remove a wasps’ nest and are not willing to wait until they expire during the cold of winter, a professional should be consulted. And be mindful that the colony’s queen can overwinter.

Bees’ and wasps’ evolutionary history is helpful to understand their behavior. Ants, bees, and wasps all come from the same evolutionary line, and taxonomists put them all in the Order Hymenoptera. Perhaps you noticed how similar they look when you’ve observed them. Ants split off from the line that eventually became bees and wasps. The common ancestor of bees and wasps was carnivorous, but after bees split into their own line, bees became vegan while the wasps still need animal food in their diet.

To understand the bees’ diet, one needs to realize that they don’t completely rely on nectar and honey for their entire lives. Like all animals, they need protein. Nectar is basically sugar water with a few amino acids and some other chemicals, depending of the species of flower and the soil nutrients available. But bees also collect pollen, a substance loaded with protein and other nitrogen-containing molecules, to fill that nutritional need. That’s the reason bees are covered with pollen-collecting hairs and wasps, which do not use pollen as food, are not.

Adult wasps on the other hand live on nectar, but they need to provision their larvae with a meat source. If you noticed how similar the hexagonal chambers of yellowjackets’ or paper wasps’ nest are to a comb in honeybee’s hive, you realize that they raise their larvae in a similar manner. While a bee lays her egg on pollen bread and seals the larval chamber, wasps seal their offspring in a chamber provisioned with a live insect. The mother wasp hunts for beetle grubs, flies, crickets or other insects. Some even collect spiders. The wasp stings its prey with a venom that paralyzes the insect, places it in a chamber, and seals it off. When the egg hatches, the larva consumes its provision of fresh meat. After ‘dinner,’ it pupates and becomes an adult wasp.

As my vegetable garden progressed from summer to fall, the fennel, with flower heads that attract small bees, flies and all sorts of wasps, flopped into the aisle next to the tomatoes which were overgrowing their cage into the same aisle. To get those tomatoes, I need to move the fennel – and the insects feeding on them. When wasps and bees are feeding, we people are a nuisance, but not a threat. If we move slowly and avoid swapping at them, they don’t care at all. Not having been stung is more than luck!

As the season has changed, there are still plenty of pollinators to observe and enjoy. We are anxious to see the monarchs start to congregate and move south. Like you, I hope monarchs decide my back yard is attractive enough that they want to spend some time resting and feeding here before continuing their journey to Mexico. Buckeyes and painted ladies are also feeding as they move south, usually to the Gulf states, for the winter. But for some real diversity and lots of action, it’s the wasps and bees that provide the most interest in the fall.