This superb collection of insect masks is from Guerrero, Mexico. The gallery owner where I purchased the pieces told me they were made in the 1940s. He also told me what he knew about the Dance of the Insectos.
The insect dance is performed during the spring. It represents change and metamorphosis. The insect goes through several different cycles and transformations. In this sense, the lifespan of an insect could be compared to a human life. We have a beginning and end, with many cycles, even if they're not as physically pronounced as an insect's.
The themes of transformation and change are fundamental in Mexican culture. The very essence of the mask itself represents transformation. The duality theme could also be seen as a cousin of the insect. They both imply the endless cycle of life, the connection between life and death, masculine and feminine, etc.