Late Summer Bees & Wasps

Martie Young
Adams County Master Gardener

Even though it is September, you are still seeing bees and other pollinators in the garden. Goldenrod and fall asters and other late blooming summer flowers will still need to be pollinated and this attracts the insects. The act of pollination may be secondary for the insects—they are really after nectar as food for themselves or their young.

At this time of year, you will see many different kinds of wasps, yellow jackets, bumblebees, and honey bees. Some are relatively benign to humans, but yellow jackets are very prevalent in this season because they are seeking sweetness and they are scavengers of garbage and food. Some of that sweetness comes from humans since this is a good time of year for picnics and fall festivals—we walk along the street with a soda, ice cream cone, or other sweet delight from a street vendor; this can lead to a sting if you don’t watch what you put in your mouth. At a picnic the wasps are attracted to fruit and watermelon. Keep all food covered except while eating it and keep a close eye on your can of soda so you don’t swallow a yellow jacket. It’s important to note that during the early part of the summer there is no shortage of nectar and insects for the yellow jacket to use as food but as the summer goes by there is more need for the wasps to scavenge their food.

Western Yellowjacket sunning on a leaf

People in general may classify all stings as coming from bees—more will come from yellow jackets and wasps (a yellow jacket is a type of wasp). Honey bees are usually too busy getting nectar and pollen from flowers, and bumblebees are just what their name implies—bumblers. If a bumblebee bumps into you or you inadvertently touch it you may get stung but it’s unlikely, but if you get too close to a yellow jacket nest or step on one in the ground, you are very likely to get stung—maybe more than once since you will really upset the whole colony.

To keep stings to a minimum, avoid using perfume or cologne and do not wear bright colors that would look like a flower. A yellow jacket can sting repeatedly and if the nest is disturbed you may be stung by more than one insect. You should not run or wave your arms but move steadily away from the nest and seek shelter (easier said than done). A bee, by contrast, can only sting once and the bee loses its stinger and then dies.

I began to notice yellow jackets in my yard and garden in August. Undoubtedly the nests were there all summer, but it took until August for the population to grow large enough to be noticeable. One nest is inside a metal clothesline pole and the other is at the edge of the eave of a shed. I know this because I observe the wasps flying into the holes and also because they cluster around the entrances to their nests—maybe it’s getting too crowded in the nest—or maybe the insects are socializing on their ‘front porch.’ Yellow jackets are said to use a nest for one year only, but they must like the location of the clothesline pole because they have come back to the same location for several years. Yellow jackets also make their nests in the ground so be careful when mowing or when digging or walking in an area that is usually undisturbed.

The life cycle of a yellow jacket or a hornet begins with the queen building a nest alone in the spring. Once she has produced enough workers to take over nest-building and foraging duties, she remains inside the nest producing more offspring. Their diet consists of other insects such as nectar, flies, bees, and caterpillars. The population of the nest can reach to 600 to 800 yellow jackets. Nests are abandoned by winter; a new queen will seek shelter alone in a protected place such as under tree bark or even attics. Since the nests are abandoned, it is usually not necessary to attempt to kill the insects or destroy the nests. The exception would be if the nest were built inside a building. It is possible for the insect to chew through the wall or find an opening into living space. If this has happened you may need a professional to remove the nest and insects.

Wasps and yellow jackets are pollinators but not as important as bees. Bees have pollen collectors on their legs and they are much more hairy than a yellow jacket so they can transport more pollen back to the hive. As the yellow jacket seeks nectar it will also transfer some pollen to another flower, thereby pollinating the flower.

Yellow jackets are classified as beneficial insects because they are predatory and eat many harmful insects including small caterpillars such as cabbage moth, gypsy moth, and many vegetable pests. Because of their quickness to sting, many humans don’t consider them at all beneficial. Even Japanese beetles, mosquitoes and aphids have some benefits, if only to feed something higher on the food chain.

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