Growing Green: Yellow jackets
In the fall, bees and wasps are on the hunt for sweets or carbohydrates, the primary energy source that keeps them flying and active for other routine activities.
The bald-faced hornet is an “aerial yellow jacket,” one of seven or eight species in the genus Dolichovespula in North America.
However, it is not a “true” hornet. It is a yellow jacket.
All of the yellow jackets in the genus Dolichovespula build nests in bushes and trees, sometimes on the outside of buildings, and produce the characteristic football-shaped, gray, papery nests.
The bald-faced hornet gets its name from the ivory-white markings on the face. The thorax, legs and abdomen also have white markings. The queen is usually the largest yellow jacket in the colony.
In the spring, fertilized queens that have overwintered in protected places such as in hollow trees, rock piles, under bark, and in the walls and attics of buildings, become active and begin to build a nest.
The queen collects cellulose from weathered and rotting wood, chews the wood adding her saliva, and takes this paste and makes a papery material to construct the nest.
She creates brood cells within the nest and deposits eggs in them and feeds the larvae when they hatch. The first brood will assume the duties of nest building, food collection, feeding the larvae and protecting the nest. As the summer progresses, the colony grows until there may be 100 to 400 workers.
Nests are usually located in bushes and shrubbery, at least three feet off the ground, and in trees, as high as 60 feet or more. Nests are sometimes found under the eaves of buildings and other man-made, protected locations.
Early in the spring and summer, protein in the form of live prey is the usual diet, consisting of flies, other yellow jackets and many other types of insects. As the season progresses and there are fewer larvae to feed, the workers will take nectar and other forms of carbohydrates. Most of the colony, other than newly-fertilized potential queens that will overwinter, will die before or shortly after the first hard frost.
Normally, most of these flying insects get their sugar fix by visiting flowers and foraging on the plant’s nectar. In late spring and throughout the summer, there is plenty to choose from.
Compare that to what is available in mid to late fall. What do you see? Not much. There are about 130 species of goldenrod in the northeastern United States. We have plenty of that around, but they don’t all bloom at once.
The only other late season wildflower that will provide some food source is aster, but it is hard to come by large, expansive fields of aster. So where can all these insects find enough sugar to get them to the end of their season?
They are resourceful and will find sugar in many places. One place is rotting or damaged fruit. Numerous landscapes have ornamental trees that produce fruit in the fall.
Crabapple is a great example as many gardeners love this early flowering tree and have the added bonus of colorful fruit in the fall. The sugar is out in the open as the fruit drops and is crushed or starts to decay.
The other sugar source is centered on human activity. Sugary snacks are readily available at picnics, trash cans, and dumpsters in soda cans and uneaten fruit.
It is wise to be a bit wary around these late-season food sources as some of these insects might sting if they feel their new food source is being threatened. Don’t worry, the cooler temperatures in the late fall will bring this activity to a standstill.
Bald-faced hornets can be considered a beneficial insect in that they reduce populations of unwanted insects (including other yellow jackets) and will help pollinate flowers when they are searching for nectar. Therefore, unless the nests are located close (within 10 feet) of an entrance to a building, under an eave that is close to the ground or in shrubbery next to a lawn that is mowed, the nests can be ignored.
However, individuals with known sensitivities to wasp and bee stings should have any nests close to their homes removed by professional pest control companies.
Spotted Lanternfly Update: Start looking for egg masses. Check the Penn State website for information on what you can do to help stop the spread of this destructive pest and how to destroy the eggs: extension.psu.edu/spotted-lanternfly.
“Growing Green” is contributed by Lehigh County Extension Office Staff, 610-391-9840; Northampton County Extension Office, 610-813-6613.