Have you ever touched the wings of a moth or butterfly and gotten some “powder” on your fingers? That powder is actually tiny scales, like on a fish or lizard, or like the feathers of a bird. These scales give butterflies and moths their scientific name Lepidoptera (from the Greek Lepido = scale, and ptera = wing). Each scale can be a different color and when placed next to each other, the mosaic makes up the color patterns we see. Some are brightly colored to warn that this species does not taste good (aposematism), or look like distasteful species (Batesian mimicry), while others look like eye spots to startle predators (image to the left), and still others form a camouflage pattern to blend in with their background.
Most colors are caused by pigments that form inside the individual scales and reflect light through holes on the scale surface (image to the right), while others, especially blues, are structural and result from light refracting off of ridged surfaces, like looking at the underside of a DVD. For more information on how blue (structural) colors are formed on butterflies watch KQED’s Deep Look episode “What gives the morpho butterfly its magnificent blue?” featuring the research of Essig Museum faculty affiliate, Dr. Nipam Patel.
To see butterfly scales under a microscope visit the Lawrence Hall of Science.
Edward S. Ross (1915-2016) was a pioneer of close up photography. Ed received his PhD in 1941 with the Department of Entomology at UC Berkeley, where he was a teaching assist for E.O. Essig. Before finishing his degree he was offered the position of Curator of Entomology at the California Academy of Sciences in San Francisco in 1939, and two years later became chair of the entomology department, a position he held for 41 years. Initially Ed was interested in Histerid beetles, but soon switched to webspinners (Embiidina), a group for which little was known at the time. His studies took him around the world, particularly to the tropics where webspinners are most diverse. During his travels Ed photographed arthropods, plants, mammals, people, and natural landscapes. His images appeared in numerous publications including National Geographic Magazine, Insects Close Up, and Insects and Plants. In 2018, Ed’s collection of ~100,000 35mm slides were generously donated to the Essig Museum of Entomology by his wife, Sandra Miller Ross, to be digitized and made available for research, education, and outreach. Once digitized, the images will be available through 
Ride, walk, or jog along the 
You have probably noticed a lot of these critters around town lately; they seem to be just about everywhere this time of year. These eye-catching little beasts go by many names, including “Cross Orb-Weaver,” “European Garden Spider,” and “Pumpkin Spider,” among others,1,2 but their proper scientific name is Araneus diadematus. (Note: common names like “Garden Spider” or “Pumpkin Spider” may refer to a number of different spider species, which is understandable given that there are an estimated 47,000 (or more)3 spider species on earth! Since we have not come up with 47,000 unique common names for all of these species, it is best to use scientific names to avoid confusion.)
not to hurt large vertebrates like us. And while a bite from one of these guys might be painful and cause a small localized reaction8 (much like a bee sting), the chances of being bitten are so slim that it is a non-issue. These spiders are not the least bit aggressive; they like to keep to their webs and mind their own business, and would only bite as a last resort (i.e. if they were about to be squished). So next time you walk through a huge web that a resident A. diadematus thoughtfully constructed right in front of your door, do not panic – the spider is running for the hills as we speak. If you are lucky, your little 8-legged buddy might stumble into your hands and let you take a closer look!
