With the annual migration of the monarch butterfly upon us, what could be more appropriate than taking a microscopical look at the fascinating structures of the colorful scales on a butterfly’s wing? In this installment of The Particle Analyst we feature the work of Taylor Lauster, a recent graduate from North Central College and Hooke College of Applied Sciences with a bachelor’s degree in Chemical Microscopy. As part of her degree requirements, Taylor decided to analyze the scales from butterfly and moth wings using the skills that she acquired during her year-long studies at Hooke College of Applied Sciences. Using polarized light microscopy, scanning electron microscopy, Fourier transform infrared microscopy, and Raman micro-spectroscopy, Taylor characterized these delicate and beautiful structures.
While setting out to study these unique particles, Taylor soon realized that knowing how to use the instrumentation is critical, but being able to sample and prepare these fragile particles takes patience and persistence. This challenging project not only helped Taylor to further develop her sample preparation skills, but being an artist, she also wanted to create an interesting image by selecting and arranging the scales from a butterfly’s wing. To do this, Taylor turned to the guidance and know-how of Senior Research Microscopist Anna Teetsov to learn a few tricks-of-the-trade on arranging these microscopic particles into a recognizable form. Anna is known throughout the world for developing pioneering particle handling techniques for instrumental analysis, and also for fun activities like arranging particles such as butterfly scales, pollen, and diatoms into works of “micro-art.” This enlarged photomicrograph of butterfly scales as a mixed flower arrangement is displayed at the entrance of McCrone Associates (Figure 1).
I thought it would be fun to show our readers a few of the key tools required to make such an arrangement yourself. There are three essential tools that you will need to make:
- A scale removal tool
- A micro-palette to store the removed scales
- A homemade rotating stage to be used on a stereomicroscope
The scale removal tool is made by scribing a glass slide diagonally and breaking it to produce a narrow piece of glass at the end of the slide, which accommodates a one millimeter square piece of Post-It®.
I was having difficulty achieving a clean break after scoring the slide with the scribe. I was told to lightly scribe the slide (less is better), and to make sure to apply pressure evenly along the scored edge using your thumbs. As a safety precaution I wore gloves and wrapped the slide in a paper towel.
The small piece of Post-It is attached to the narrow glass slide by using an equally small piece of double-sided tape (Figure 2). Make sure to have the sticky part of the Post-It facing up; this will allow you to attach a piece of one millimeter membrane filter paper to the sticky part of the Post-It. The filter paper acts as the substrate to collect the scales from the butterfly wing (Figure 3). The scale removal tool allows you to collect a large amount of scales from a particular area of interest (color) on the butterfly wing.
Next, you will need to create your own artist’s micro-palette of butterfly scales. Each area of the butterfly’s wing will contain scales of different shapes and colors that can be deposited onto your micro-palette, which you will use when choosing a scale of the right shape and color for your artistic creation.
Similar in construction to the scale removal tool, the micro-palette uses a standard microscope slide with a strip of double-sided tape running down the middle of the slide. A narrow length of Post-It is attached—sticky side up—to the tape. This narrow length of Post-It will hold small square pieces of colored Post-It paper (Figure 4). You will then cut out equally sized square pieces of filter paper, roughly three millimeters square which will ultimately accept the scales from the scale removal tool. I used a 45 millimeter mixed cellulose ester (MCE) filter with a grid pattern (Figure 5). Each square will contain a particular color of scale, this is your micro-palette (Figure 6).
When you cut the small pieces of the colored Post-It for your micro-palette make sure to include the triangular tab along one edge, which acts as a handle. The tab is helpful to have when you go to move an individual palette color to the rotating stage for closer proximity to your coverglass canvas. (Figure 7).
Collecting Butterfly Scales
The idea is to gather the scales using the scale removal tool by simply touching the filter paper to areas of interest on the butterfly’s wing. Next, carefully deposit the scales onto one of the larger pieces of filter paper on your micro-palette by touching the scale remover filter to the micro-palette filter. The MCE filter is “sticky” enough to remove the scales from the wings, but not too sticky as to not transfer the scales to the palette (think the Locard Exchange Principle: with contact between two items, there will be an exchange). You will need to change the scale remover filter each time you want to sample a different area (color) of the wing to keep from colors on your micro-palette.
The Rotating Stage
The homemade rotating stage makes it easier to place and orient each scale. To make the rotating stage, you will need to purchase a 1-1/2 inch flanged ball bearing. Anna recommends that you clean the bearings with hexane prior to use in order to remove the heavy lubricant within the bearing assembly.
Next, find a slightly smaller diameter metal washer that will act as both your sampling stage and a platform for your micro-art canvas. Attach a piece of Post-It to the metal washer using double-sided tape. Make sure to create a hole in the Post-It to allow light to travel through what will be your micro-art canvas. To stabilize the washer to the ball bearing, you can use small pieces of furniture pads (the kind you would use on chair feet to prevent scratching a hardwood floor). These small pieces of furniture pads should be cut to fit into the groove of the ball bearing, acting as guide pins so that the washer will remain in place (Figure 8). Take a round coverglass and coat it with a soluble adhesive. Anna recommends using a small piece of adhesive from the back of a piece of tape dissolved into a small drop of amyl acetate. Carefully place the coverglass, coated side up, in the center of the stage. Notice the addition of four small pieces of Post-It around the opening acting like a target to guide your placement of the coverglass (Figures 9 and 10).
Creating Your Art
Now you are ready to start creating your image. Using a tungsten needle, lift some of the scales from your micro-palette and place them onto the stage just surrounding the coverglass canvas. Once you have accumulated a sufficient number of scale colors and sizes, you will then be able to select individual scales using a tungsten needle.
After hours of practice, Taylor carefully arranged the individual scales from butterflies’ and moths’ wings into the form of another winged creature, an owl (Figure 11). To give you an idea of the scale Taylor was working at, the entire arrangement uses 35 individual scales and covers an area of about one square millimeter.
While the monarchs are wintering in Mexico, you can begin making the tools and honing your skills to create an interesting scale arrangement of your own.