Hornets and Yellow Jackets

By Jeanne Henderson


People avoid certain insects because of the stings they can inflict. Bees and wasps go about their daily activities without encountering people the vast majority of the time, and we hardly know they exist. When they build their hives close to homes, or hide their nests underground, they may turn into a dangerous nuisance. Learning to understand their beneficial ecosystem roles helps us appreciate them, especially from a distance.

Bees, hornets and wasps will sting to defend their hives or when they feel threatened by an animal or human who comes too close. Bees are herbivores that consume nectar and gather pollen to feed their developing young, pollinating wildflowers, fruits and vegetables in the process. Wasps include solitary and social species that are herbivores as adults, drinking nectar and also pollinating flowers. Wasp larvae are carnivores, relying on their wasp parents to provide a steady diet of insects. Being efficient predators, wasps help control insect pests that might otherwise claim too much of our food crops.

Bald-faced hornets build the most visible nest, often reaching the size of a basketball. The queen that overwintered under logs and leaf litter emerges in spring. She gets energy from early blooming flowers to start building a new colony. She makes a small upside-down comb, not from wax like honeybees, but from her saliva and wood fibers she scraped from a tree. Next she builds a bell-shaped paper cover over the cells, with a long tube and entrance at the bottom, which reduces heat loss from the developing eggs she laid in the cells. The first mature offspring are all females, smaller and sterile, becoming workers for the hive (similar to a honeybee colony). Hornets pounce on prey, hold it with their legs and transfer it to their mandibles where they chew it into pulp mixed with saliva to feed to their young. As the colony grows, workers build stacked layers of combs with brood cells covered by more paper layers.

Hornets defend their hives from squirrels and birds that would devour the grubs if they could. Guards posted at the entrance hole rush out to attack any foreign body nearby. Waves of hornets follow, stinging the intruder with extremely painful venom as it runs to escape.

  • Yellow jackets nest in the ground, using old chipmunk holes or mole tunnels. In their paper combs, they lay one egg per cell, provisioned with prey insects. Their yellow and black striped bodies are distinctive. Besides being predators, in the fall they feed on apples, pears and rotting fruit, or visit open garbage cans to scavenge leftovers.
  • Paper wasps are dark colored with dull yellow or orange markings. They construct an umbrella-shaped comb of cells, a single row of about 100 cells with openings at the bottom. Made of chewed wood and saliva, the nest hangs from a horizontal surface supported by a single paper stalk.
  • How to tell if you are looking at a wasp, bee or fly? Wasps, hornets and yellow jackets (in the same family Vespidae) have these characteristics: a long body shape, long antennae, eyes on the side of the head, a pinched waist between the thorax and abdomen and are relatively hairless. When resting, Vespidae hold their folded wings slightly out to each side of the body, not over their back like other wasps. Bees come in a variety of colors and sizes, so look for a compact body, usually hairy, a robust waist and pollen-collecting hairs or baskets. Flies have one pair of wings, short antennae, large eyes that make up most of the head, no defined waist, a compact shape and some hairs.