Hemolymph Flows in Butterfly Wings

Butterfly wing stain

Appearance of dye from the hemolymph in the wing veins of Pieris rapae 0 to 18 h after injection into the hemolymph.
Image: Wasserthal*

Butterfly wings are produced by two layers of cells, and upper and lower layers. The cells degenerate and the upper and lower surfaces are tightly opposed and joined over much of the wing surface. In appropriate locations, the wing surfaces are separated by distances that form tubular structures or wing veins. The wing veins may contain trachea for respiration and nerves for sensors on the wings. The veins are filled with fluid from the hemolymph.

Wasserthal was able to stain the wings of Pieris rapae by injecting dye into the tip of the abdomen of a tethered, resting butterfly. Images of the wings at time intervals after dye injection demonstrate the movement of hemolymph into the wings along the veins. Wasserthal suggested that the fluid might oscillate somewhat but was mostly unidirectional flow from the hemolymph to the wings. Water lost to evaporation from the wings would be replaced by fluid from the hemolymph. This mechanism would allow the deposition in wing tissue, substances dissolved in hemolymph such as chemicals toxic to predators. The toxins could flow one way into the wing and accumulate there.

*Wasserthal, L.T. Haemolymph flows in the wings of Pierid butterflies visualized by vital staining. Zoomorphology(1983) 103:177-192.

About jjneal

Jonathan Neal is an Associate Professor of Entomology at Purdue University and author of the textbook, Living With Insects (2010). This blog is a forum to communicate about the intersection of insects with people and policy. This is a personal blog. The opinions and materials posted here are those of the author and are in no way connected with those of my employer.
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