occurs at a relatively low frequency. White monarchs (D. p. p. "form nivosus") have been found throughout the world, including Australia, New Zealand, Indonesia, and the United States. However, some taxonomists disagree on these classifications. Genome The monarch was the first butterfly to have its genome sequenced. The 273-million-base pair draft sequence includes a set of 16,866 protein-coding genes. The genome provides researchers insights into migratory behavior, the circadian clock, juvenile hormone pathways, and microRNAs that are differentially expressed between summer and migratory monarchs. More recently, the genetic basis of monarch migration and warning coloration has been described. No genetic differentiation exists between the migratory populations of eastern and western North America. Recent research has identified the specific areas in the genome of the monarch that regulate migration. No genetic difference is seen between a migrating and nonmigrating monarch, but the gene is expressed in migrating monarchs, but not expressed in nonmigrating monarchs. A 2015 publication identified genes from wasp bracoviruses in the genome of the North American monarch leading to articles about monarch butterflies being genetically modified organisms. Life cycle Metamorphosis Like all Lepidoptera, monarchs undergo complete metamorphosis; their life cycle has four phases: egg, larva, pupa, and adult. Monarchs transition from eggs to adults during warm summer temperatures in as little as 25 days, extending to as many as seven weeks during cool spring conditions. During their development, both larvae and their milkweed hosts are vulnerable to weather extremes, predators, parasites, and diseases; commonly fewer than 10% of monarch eggs and caterpillars survive. Egg The egg is derived from materials ingested as a larva and from the spermatophores received from males during mating. Female monarchs lay eggs singly, most often on the underside of a young leaf of a milkweed plant during the spring and summer. Females secrete a small amount of glue to attach their eggs directly to the plant. They typically lay 300 to 500 eggs over a two- to five-week period. Eggs are cream colored or light green, ovate to conical in shape, and about in size. The eggs weigh less than each and have raised ridges that form longitudinally from the point to apex to the base. Although each egg is the mass of the female, she may lay up to her own mass in eggs. Females lay smaller eggs as they age. Larger females lay larger eggs. The number of eggs laid by