Re: Why do groups of yellowjacket wasps remain motionless outside of their nest

Dear Stuart,

Social insects are fascinating, and wasps are a common social insect that is easy to observe. (Just watch out for the stings!) Yellowjacket is the name given to two genera of wasp found throughout the United States, Vespula and Dolochovespula. All wasps are members of the Order Hymenoptera, which also includes social bees and ants. Not all Hymenoptera (and not all wasps) are social insects, and the reason for the evolution of this complex life pattern is fascinating. If you'd like to read more about it, there is a fantastic explaination given on Rice University's Deapartment of Ecology and Evolutionary Biology's webstire.

The larger wasp you see is probably the nest's Queen. She was probably born late last summer, and after being fertilized by a drone, she went into a kind of hibernation called diapause over the winter, while the rest of her original nestmates died off in the cold. In the early spring, she began constructing a new nest, in the overhang of your balcony, out of plant fibers. Once she grew strong enough, and the first, small nest was prepared, she laid her first batch of eggs, and tended them until they grew into adult wasps.

Once the second batch of yellowjackets are produced, the Queen stops going off on hunting trips of her own, and relies on the growing number of wasps to keep her fed while she concentrates on producing as many young as possible. Because you see the larger wasp flying, it sounds like the colony has not yet produced the second batch of yellowjackets that liberate the Queen from such tasks.

The yellowjackets that stay on the nest have several functions. These include guarding the nest against attack and keeping the nest clean and well constructed. If the nest is already well cared for, then the wasps sit still on the nest, waiting for any threat to present itself. (It is more energy efficient for them to simply sit on the nest and wait, than to fly around, which is why they are so still.)

When the Queen (or any other member of the nest) comes home from hunting, there is great excitement. There is a lot of information for the Queen to tell the guardians, and information for the guardians to tell the Queen. The information is passed through pheromones, which are hormones that can pass outside of the body. The wasps are communicating with chemicals!

Additionally, the arriving Queen may have found a great source of food or water, and may be passing out some to the guardians to nourish them. This sharing of food is very important in all social insects, and is called generally called tropholaxis. The food and/or water is regurgitated from the wasp that was out foraging into the mouths of the wasps that need the nourishment.

Colorado Sate University's website has a page filled with more information on yellowjacket biology, including how to recognise and treat sting allergies, and much, much more. Want to get rid of a wasp nest? Another MAD Scientist, Unc le Al Schwartz, has a suggestion.

There are many great websites and books on the biology of wasps. The information presented here comes mostly from a fantastic book that I was given by one of the authors, The Yellowjackets of America North of Mexico, which is a US Department of Agriculture Handbook for sale by the Superintendent of Documents, US Government Printing Office, Washington, DC 20402.

Full citation: Akre, R.D., A. Greene, J.F. MacDonald, P.J. Landolt, and H.G. Davis. 1980. Yellowjackets of America North of Mexico. U.S. Department of Agriculture, Agriculture Handbook No. 552, 102 pp.


Thanks for writing the MAD Scientist Network. I hope this answer provides you with more thoughts about the fascinating things you can find in your own back yard. If you have any more questions about social insects, or other scientific area, please write us again!


Sincerely yours,

John