Over the flower-decked prairies, West;
basking in sunshine till day light is dying,
and resting all night on Asclepias, breast:
Chasing his lady-lore high in the air,
Free from anxiety, sorrow, and care!
Hundreds of eggs will be laid by a female Monarch within her life-span. These pin sized eggs are deposited one at a time on milkweed leaves; these are the only plant which the larvae can survive. The creamy-yellow eggs take three to six days to hatch, depending on the temperature.
Larvae or Caterpillar
The newly hatched larva is less than 1/16 of an inch long. During the next 15 to 20 days the caterpillar feeds voraciously on the leaves and flowers of the milkweed and increases its weight by a factor of 2,700!
Monarchs and Milkweed
For about half the year, milkweed is the butterfly’s home, food supply and maternity ward. The Monarch larva eats only milkweed. The poisons contained in these plants are absorbed by the larva and remain in the adult Monarch butterfly. This poison often discourages potential predators who may become sick after eating a Monarch and learn to avoid them.
Pupa or Chrysalis
The larva seeks a safe, sturdy place to hang while it undergoes metamorphosis. The caterpillar dangles upside down and curls its body into the shape of a letter ”J”. After 15 to 20 hours the larva sheds its skin to reveal its bright green chrysalis underneath. During the next 10 to 15 days, the tissue of the caterpillar breaks down within the chrysalis and the butterfly’s body forms.
Adult Monarch Butterfly
Clinging to the skin of the chrysalis, the newly emerged butterfly pumps body fluid into its crumpled wings, making them expand; with the help of the sun the wings will dry and harden over the next several hours. Less than 3 hours after emergence, the adult Monarch is ready to explore its new world.
Monarchs are unable to survive extended periods of freezing temperatures in any stage of their life cycle. Therefore while they are able to exploit the extensive North American milkweed flora during the summer, expanding their range, they must migrate to less extreme climates to spend winter.
It is likely that most of the Monarchs east of the Rocky Mountains migrate to mountains in Southern Mexico to spend the winter, while those West of the Rockies fly southwest to the California coast. In early October, as a decrease in daylight hours signals the coming of winter, substantial numbers of Monarchs begin to appear. They may travel to the coast from as far away a Montana or Canada. As Monarchs migrate to over-wintering locations, they seek flower nectar sources along the way to build up fat reserves for the coming winter.
During this migration, they glide on the wind in solitary flight and cluster in small numbers at night; with arriving winter storms they abandon temporary roost sites and seek shelter in more protected, over-wintering locations.
Over-Wintering and Mating
Once Monarchs reach their over-wintering sites, they begin to group together into clusters. Their combined weight helps keep them from being dislodged by the wind and rain. Since Monarchs have difficulty flying at temperatures below 55 F, dislodged butterflies often end up on the ground in cold weather. During late January and early February, increasing daylight hours signal reproductive instincts in Monarchs. On warm afternoons during the mating period, courting pairs drift down like falling leaves. Once on the ground the male attempts to couple with the female. If he is successful he carries the pair, with the female dangling passively below, up into a nearby tree branch. The pair may remain coupled overnight as the male passes a nutrient rich spermatophore into the body of the female. The female produces fertile eggs and uses the nutrients to help power her flight over the mountains on her return migration in February. She will seek out inland milkweed patches to lay her eggs before dying.
There is still much speculation about how the Monarchs return to the same over-wintering grounds. The earth’s magnetic field, the position of the sun and geographic features of the land are components of navigation likely to be involved in the mystery of Monarch migration. There are still many aspects of Monarch natural history which we have yet to fully understand.
So Plant Milkweed Seeds for a Butterfly Garden!