Entomology (Study of Bugs)/Paper wasp behavior

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Question
Dear Bug Eric, On my sagebrush steppe land I grow a lot of large native sunflowers to benefit insects, birds and mammals. The plants' flowers are popular with flies, bees, wasps and ants alike, but the ants and wasps also spend a great deal of time on the stems and leaves. I have noticed this year that my paper wasps-- what we used to call "yellowjackets" -- are spending much of the day clinging to the undersides of the sunflower leaves. I have also seen them just clinging for a long time on the stems. I could not see that they were getting any fibers from leaf or stem-- and indeed, my wasps seem to be having trouble building nests his year, so far I have only one very small attempt and it is not expanding even though the season is coming to a close. Weather has been very dry and windy but I water native plants to provide nectar sources-- still, although I have wasps, they just aren't building as they used to. And I don't ever recall individuals spending so much time just hanging around on the undersides of leaves. Perhaps I simply did not notice the behavior before. What are they doing? I do not use pesticides of any description on my land, and we are set back an eighth of a mile from the dirt road. Thanks for your help. Laura

Answer
Laura:

Without seeing images of the wasps, I cannot agree that they are paper wasps, but here in Colorado they certainly like sunflowers....

Sunflowers have "extra-floral nectaries" that attract wasps, flies, bees, ants, etc, and the stems and leaves seem to secrete a sweet, sticky substance.  The flower buds are most attractive in my observations.

During the heat of the day, many insects seek shade wherever they can find it, and that might also explain why the wasps are hanging out on the underside of leaves (conversely, they also seek shelter from rain under leaves).

Thank you for sharing your observations, I am most impressed :-)

Eric

Entomology (Study of Bugs)

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Eric R. Eaton

Expertise

I answer insect and spider identification questions ONLY. Attach images if possible. No "what bit me?", "what do I feed this bug in captivity?", or science fair project questions please. NO TECHNICAL QUESTIONS ABOUT INSECT PHYSIOLOGY.

Experience

Principal author, Kaufman Field Guide to Insects of North America. Professional entomologist employed previously at University of Massachusetts, Chase Studio, Inc., and Cincinnati Zoo; contract work for West Virginia Department of Natural Resources, Smithsonian Institution, and Portland (Oregon) State University.

Publications
Author, Kaufman Field Guide to Insects of North America, Missouri Conservationist magazine, Ranger Rick, Birds & Blooms, Timeline (journal of the Ohio Historical Society). I have contributed to several books as well.

Education/Credentials
Oregon State University, undergraduate major in entomology, did not receive degree.

Awards and Honors
One of the top 50 experts in all categories for AllExperts.com, 2009.

Past/Present Clients
Principal author of the Kaufman Field Guide to Insects of North America, Smithsonian Institution (contract), Cincinnati Zoo (employer), Portland State University (contract), Chase Studio, Inc (employer), Arkansas Museum of Discovery (guest speaker). Currently seeking speaking engagements, leadership roles at nature festivals, workshops, and ecotours.

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