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“LADYBUG, ladybug, fly away home…” These tiny polka-dotted insects invariably complied with this childhood entreaty so quickly that I knew nothing about their winged travel.
Coccinellidae are known as ladybugs in North America, ladybirds in Britain and other parts of the English-speaking world. The name originated in Britain as “Our Lady’s bird,” the Virgin Mary often depicted in early paintings wearing a red cloak. The insect’s seven spots were said to symbolize the Catholic Church Mary’s seven joys (Annunciation, Nativity of Jesus, Adoration of the Magi, Resurrection of Christ, His ascension into heaven, the Pentecost and Mary’s coronation in heaven); there are related seven sorrows as well.
The German name Marienkäfer translates to Marybeetle, correctly identifying this insect as a beetle, not a true bug. Beetles have hardened front wings; true bugs, the Hemiptera order, do not.
These hardened front wings are called elytra, and they provide protective covering for the ladybug’s magic: Its hind wings unfold to be four times the ladybug size. Yet these primary wings are deployed in only a tenth of a second and retracted origami-like in just two-tenths.
Little was known about the ladybug’s quick transition from walking to flying until Japanese researchers applied methodology that, in its own way, is as fascinating as the ladybug’s wing deployment and retraction. It’s described in “Investigation of Hindwing Folding in Ladybird Beetles by Artificial Elytron Transplantation and Microcomputed Tomography, by Kazuya Saito et al.
Saito and his colleagues at the University of Tokyo, the National Museum of Nature and Science, and Kyushu University note in the paper’s abstract, “Researchers have found that the intrinsic elasticity acting in wing veins allows this high-speed deployment. Investigation of other species of beetles indicated the existence of a hydraulic mechanism that straightens the wing veins. In contrast, the other fundamental problem, namely the mechanism behind the folding of these wings, remains unclear. Complicating matters further is the fact that ladybird beetles close the elytra ahead of wing folding, preventing the observation of detailed folding processes.”
The researchers addressed this second aspect by fitting their test-subject ladybugs with transparent acrylic elytra and observing the wing folding using high-speed photography. The fabrication of these acrylic elytra was itself a daunting and delicate project.
Researchers studied the folded storage of the hind wings using microcomputed tomography. Micro-CT is a non-invasive means of analysis. It takes many microimages of the object, then uses computer algorithms to assemble these into cross-sectional (tomographic) slices.
The hind wings fold in and over to form a Z shape, their veins bending into cylinders. For deployment, these veins are energized hydraulically and act like tiny springs, thus giving the ladybug’s rapid transition into flying mode.
Researchers note practical applications of this ladybug art in engineering science. Satellites, for instance, are launched with large solar panels folded for compact packaging. Once in orbit, the panels are unfolded, deployed and made rigid.
Polka-dots are optional. ds
© Dennis Simanaitis, SimanaitisSays.com, 2017