A Taxonomist's Focus
“[Nabokov’s] technique of measuring the patterns of scales by counting, numbering, and quantitatively comparing their rows was a novel and ingenious new method...”
– Robert Michael Pyle in "Between Climb and Cloud" published in Nabokov’s Butterflies (2000) p. 58
As a taxonomist Nabokov studied butterfly's wing characters, coloring, and genitalia to help identify and distinguish between different genera and species. His theory of the origins of the Polyommatus Blues in the Americas was also based on morphology, especially on the close study and microscopic comparison of male genitalic structures.
Wings & Scales
The scales of butterfly and moth wings are not only beautiful and functional in a variety of ways, they are also very important in taxonomic identification, both in the color patterns that they create on the wings and body, as well as the shape of the scales themselves.
Each scale is a complicated structure that can have ridges and border ornamentation–they are individually socketed and are deciduous, so they can fall off without damaging the insect. Underneath the scales, the wings are clear and gossamer, and some practices would preserve an example of a scale-less wing for study.
Some moth scales are textured to absorb echolocation from bats and disrupt the hunt, and some are part of a complex series of pheromone dispensers for communication.
Genital Structures
Many insects are visually similar and can only be distinguished via examination of the genitalia. Unique genital structures distinguish individual species, as the structures are elaborate and complex in both male and female lepidopterans. All these structures are involved both in physical coupling (holding the abdomens together) as well as sperm transfer to the correct location. There is a long history of dissecting the genitalia of different butterflies and moths to carefully examine and compare these diagnostic characters. This is a time-intensive and delicate process that takes patience and a careful hand.