Thursday, June 13, 2024

This common aerial yellowjacket, like all wasps, has a narrow waist that separates the middle segment from the abdomen. (Photo: Tom Murray)

There are 30,000 species of wasps. The vast majority (29,000) are solitary creatures that nest in the ground and are not likely to sting because they do not defend their nests. These wasps help keep insect and spider populations in check, and they avoid people whenever possible.

Contrast this behavior with social wasps such as yellowjackets, which do defend their nests. They live in colonies much like ants or honeybees. Most of the wasps in the colony are workers who gather food and care for the queen’s offspring.

A yellowjacket queen built this nest on the underside of a board in Groton in June 2020. (Photo: Tom Murray)

A yellowjacket queen overwinters in a safe spot. In the spring, she emerges and builds a small nest with about 45 to 70 eggs that hatch into larvae. The queen feeds the larvae with insects and scavenged meat until some have matured into female worker wasps. Then the workers take over all duties except egg laying. The queen lays more and more eggs, and the workers expand the nest, collect insects and meat to feed the new larvae and defend the nest. By late summer, the colony can have thousands of wasps. 

Adult wasps search for foods high in protein, such as insects and meat, to feed the larvae. They chew this food into a paste the larvae can ingest. The larvae in return secrete a sugary substance through their salivary glands that the adult wasps eat. 

A common aerial yellowjacket in Hudson, New Hampshire, on Aug. 22, 2021. (Photo: Tom Murray)

In late summer, the queen stops laying eggs except for those that will become males and new queens. She no longer releases a chemical, called a pheromone, that elicits submissive behavior and keeps the workers working. Without this pheromone, the worker wasps no longer stay near the nest. Without enough larvae to feed and be fed by, the wasps scavenge for alternate food such as sugary drinks or fruits on picnic tables. Worker wasps at this time of year are near the end of their three-week life cycle, and they are hungry and aggressive.

These late-summer worker wasps have few or no duties and spend their time searching for nectar and sugary meals, such as that watermelon at your cookout. If you panic and swat one, it releases alarm pheromone molecules that travel through the air, signaling to other nearby wasps that it is under attack and needs help. The nearby wasps enter attack mode to protect their nest (likely nearby) and one another. And, unlike bees, each wasp can sting multiple times.

An eastern yellowjacket on a flower in Lancaster on Oct. 16, 2022. (Photo: Robert Gessing)

To keep from setting off wasp alarm signals, stay calm around wasps (easier said than done). You can put a bowl of sugary liquid on the other side of the yard from where you sit. The hungry wasps will be attracted to this sugary meal and with luck will leave your picnic alone.

Also in late summer or fall, hundreds of new queen wasps and males hatch. The queens grow fat in the colony before they leave. The males are kicked out when they become adults. The males fly away and mate with new queens from other colonies. Then they die. The new queens store sperm in their reproductive tracts until they need it to fertilize eggs in the spring. These fertilized queens look for a safe place in which to overwinter, such as leaf litter, a hole in the ground, a hollow log, firewood or wall siding. Cold weather kills the worker wasps, leaving only the queens to overwinter and start new colonies in the spring. Most of the overwintering queens do not survive. They are hardy and can survive harsh weather, but spiders and birds eat many of them. By spring only a few have survived.

A widow yellowjacket in Lincoln in August 2022. (Photo: Norm Levey)

Social insects such as yellowjackets have many glands, mostly on the head, that secrete pheromones to communicate important functions. Sex pheromones help males wasps attract mates and mark territories. Alarm pheromones help wasps defend their nest. And queen pheromones signal the workers how to behave.

As we all know, many yellowjackets are shiny with yellow and black markings. Yellowjackets, like all wasps, build nests. People use wood to make paper, and so do wasps. Wasps scrape fibers off wood and chew the fibers, mixing them with saliva, to make a papery pulp with which to construct a nest. Yellowjackets build papery nests, but you often do not see them because they are in the ground, in a log or sometimes behind the walls of a building. You might see yellowjackets hovering near a hole in the ground, which is probably the nest opening. A yellowjacket nest lasts for only one year. These wasps usually do not reuse old nests.

An eastern yellowjacket drinks in Groton inn August 2023. (Photo: Tom Murray)

Yellowjackets are beneficial creatures who seek out insects to feed their young. They feed their larvae crop-damaging insects such as aphids, beetles, fly maggots and cabbage worms. Without wasps, our planet would be overrun with insect pests.

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Reader photo

Eileen Peri sends this photo of a praying mantis.

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Jeanine Farley is an educational writer who has lived in the Boston area for more than 30 years. She enjoys taking photos of our urban wild things.