The Gyrinids are the most easily-recognized family of the order Coleoptera inhabiting water. The brilliant steel-blue or black whirligig beetles are often seen gyrating in groups on the surface of the quiet water of ponds and streams. They are such agile swimmers that it is difficult to capture them without a net. When captured, the beetle secretes a milky fluid with a disagreeable odor although in some species the odor suggests ripe apples. The food consists of other small insects that fall into the water.
Proceedings of the Iowa Academy of Science
©1950 Iowa Academy of Science, Inc.
Schaffner, J. C. and Millspaugh, D. D.
"A Preliminary List of the Gyrinidae (Coleoptera) Known to Occur in Iowa,"
Proceedings of the Iowa Academy of Science, 57(1), 531-532.
Available at: https://scholarworks.uni.edu/pias/vol57/iss1/78