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Summer 2010

Urban Jungle

The changing natural world at our doorsteps | Illustration and text by Patterson Clark      

September 21, 2010

Yellow jacket delirium

As the nest's social structure dissolves with the onset of autumn, unemployed yellow jacket workers behave erratically, increasing people's risk of stings.

The subterranean colony began last spring with a queen emerging from hibernation. In an abandoned rodent burrow, she built a small paper nest of about 40 cells, each hosting an egg. After a week the eggs hatched, and for 12 days the larvae were fed masticated meat and insects by their queen. After 12 days of pupating, mature workers emerged and assumed all labor so that the queen could focus only on laying eggs.

Over the summer the nest grew to as many as 5,000 workers.

Workers and larvae developed a special relationship. As workers fed chewed-up insects -- many of which are agricultural pests -- into the mouths of larvae, the larvae reciprocated with drops of sweet liquid from their salivary glands, an addictive incentive for the workers to return with more food.

As summer winds down, the queen has stopped producing workers and deposits only queen and drone eggs. When they emerge, the two sexes mate, the drones die and the fertile queens eventually seek an overwintering spot in leaf litter or under the bark of a rotting log.

Meanwhile, thousands of aggressive yellow jacket workers are out of a job and wandering aimlessly, their sweet tooth targeted at oozing fruit and sugary soda cans.

Eastern yellow jacket, Vespula maculifrons

Sources: University of Florida Institute of Food and Agricultural Sciences, University of Michigan Museum of Zoology, Journal of Family Practice, Houston Audubon Society