It's time to watch the skies and trees for the flutter of black and burnt-orange of Monarch butterflies flitting their way south to Mexico.

Mid- to late September is the time of year these beautiful creatures wing their way through Kansas on their way to their wintering grounds. The amazing migration of these delicate creatures has long been a mystery to mankind and is a unique phenomenon in the insect world.

As children, most of us learned about the fascinating metamorphosis of butterflies from egg to caterpillar to chrysalis, with the final transformation into a vibrantly colored beauty.

The rest of the story is every bit as extraordinary. It is fairly well known that the bold colors of the monarch serve as a warning to predators pronouncing: "I taste awful!"

In the case of the monarch, their diet of milkweed causes this unpalatability. This plant and animal pair are intimately linked together as milkweed is the main food source for the larval stage of this butterfly.

Monarchs usually begin their migration in Canada, farther north than any other North American butterfly. One hundred million to half a billion butterflies are thought to make the journey, which, unlike the migration of waterfowl or bird species, is a one-time trip.

But let's back up a bit to see what leads up to this incredible butterfly adventure. Most butterflies only live about two to six weeks during the summer months. With many other species, mating takes place soon after the butterfly emerges from its cocoon.

With many monarchs, however, they wait until they mature (a whopping four to six days!) before they mate. Females produce hundreds of eggs (400 to 700 have been counted in captive specimens), with the number affected by the availability of nectar, the abundance and condition of milkweed and weather. Three to six generations hatch each year, repeating this same cycle emerging, dispersing, mating and laying eggs until they die at four to five weeks of age.

The final generation has a slightly different plan in store for them. Monarchs emerging in August and September somehow know how to delay their maturation.

Cool nights and shorter days may trigger the urge to migrate. They gorge themselves on nectar-laden flowers, converting the sugar to large amounts of fat necessary for surviving the long journey south. (The thought of fat butterflies is kind of hard for me to picture!)

The migration is necessary to prevent butterflies from freezing to death in winter. The preferred cool mountain forests of Mexico apparently provide ideal temperature and humidity levels for surviving the winter. If the air is too warm, they use up their energy reserves too quickly, and won't survive until spring to lay eggs. If it is too cool, they could perish.

It also has been noted that removing even a few trees from these important forest habitats changes the high humidity level, and can have serious repercussions on monarch winter survival. Their inactive state, brought on by cool but not freezing temperatures, allows them to survive longer than preceding generations.

Those butterflies that successfully complete the journey, avoiding predators, collisions with vehicles, starvation, inclement weather or even getting lost, arrive at their wintering grounds in coastal California (for monarchs from west of the Rockies) and south-central Mexico (for those living east of the Rockies).

The sight of 60 to 300 million monarchs blanketing the trees and bushes is breathtaking. Sadly, only about 1 percent of the wintering population survives to return north in March, but this is enough. None are thought to make it back to their own birth place, but rather lay eggs and die along the way, starting the cycle all over again.

Attention has been focused in recent years on conservation of the critical overwintering habitat of monarchs, and much progress has been made. The cool mountain forests of Mexico have been threatened by logging, development and even by tourism for those who travel to see the spectacle of butterflies themselves.

Lately, local residents have been reporting the gathering of monarchs in great numbers on trees in our area. It's hard not to stop and admire them for a bit before returning to our hectic schedules. Next time you see a single monarch flitting erratically by, you'll have a better appreciation for where they are headed and where they have been.

If you'd like to increase your chances of attracting butterflies to your yard, consider adding some butterfly bushes, butterfly or other species of milkweed, or other flowering plants that provide nourishment for these delicate and beautiful creatures.

You also may spy some of these winged wonders at our butterfly garden near the elephant exhibit at the zoo.

Visit our award-winning Web site at www.garden-city.org/zoo.