It snowed today in the Neovolcanic mountains northwest of Mexico City. Next year there will be fewer Monarch Butterflies in the Southern Appalachians. Such are the connections in the web of life, whose gossamer strands stretch from Mt. Mitchell to Altamirano and beyond.

The large, black and orange Monarch Butterfly, a familiar summer visitor to roadside and garden flowers in our area, is one of the few insects that migrate south in winter. Most of its six-legged relatives expire with the first freeze, leaving only eggs, larvae or pupae to over winter.

The Monarch, however, believes in affirmative insect action and undertakes a 2000 mile flight to a winter refuge in upper-elevation forests on the slopes of Central Mexican Mountain peaks from Altamirano to Los Palomas. It spends the winter months in groves of pine, fir, and cedar trees where the temperature normally hovers near 40 degrees throughout the winter and frosts seldom occur.

The final days of 1995 were different, however. With up to twelve inches of snow on the ground in their winter refuge, environmentalists were predicting the demise of the Monarch Butterfly species. National network television news highlighted the Monarch's "fight for survival." How could an organism as delicate as a butterfly survive this disaster?

Well, the fire of life burns fiercely in the black and orange Monarch. Although death rates of 15% to 35% were reported for the overwintering colony, the reproductive potential of this "delicate" organism is more than sufficient to make up for the loss.

Consider the following Monarch Mathematics: A single female Monarch Butterfly may lay 300-700 eggs in her lifetime. Let us use a conservative average of 400 eggs per female in our calculations. Monarchs mate at or near their overwintering area and scatter eggs on milkweed plants growing along their return route. Descendants of a single Monarch female, hatching in Texas, Louisiana and Mississippi next April, can potentially number 400 butterflies, with 200 being female.

The 200 females continue the northward flight, passing through North Carolina, each having the potential to leave 400 offspring. This second 1996 generation of Monarch Butterflies, if all were to survive, would consist of 80,000 individuals, including 40,000 females.

The 40,000 females, descendants of a single fertile female from the Mexican highlands, could potentially lay 16 million eggs, half of which might grow into female Monarch Butterflies. This is the 1996 generation which would enjoy the midsummer wildflower meadows from Ohio to Ontario and New England. The eight million females might potentially scatter more than 3 billion eggs. Thus, within a single female Monarch Butterfly burns a flame bright enough to replace the entire Eastern North American Monarch Butterfly population within a single year. This is the "biotic potential" of the Monarch Butterfly.

Of course, most butterfly eggs do not survive to become breeding adults. On average, only one out of every 200 eggs escapes predation, disease, and accident during the miraculous transformation from egg to caterpillar to chrysalis to butterfly. However, each female Monarch needs only to produce, on average, two mature butterflies to maintain a stable population. The two progeny would replace the mother butterfly and her mate.

If half the butterflies of Altamirano do not survive the winter, each breeding female need only produce four surviving offspring to make up the loss. Survival of one egg in a hundred in the first generation would be sufficient to overcome 50 % mortality in the overwintering site.

And with reduced competition for egg laying sites (female Monarchs will not lay an egg on a milkweed leaf which already contains a Monarch egg), the reproductive success of each remaining female would be expected to increase. Fewer and more widely spaced Monarchs would also reduce the spread of disease and parasitism of caterpillars, further enhancing the survival of individuals.

So the Monarch Butterfly is not fighting for survival. It is merely experiencing a downward cycle in its naturally varying population level. Next year will very likely be a "poor" Monarch year in the Southern Appalachians and throughout Eastern North America.

On the other hand, it will likely be a good year for milkweeds, and a poor year for Monarch diseases and parasites. Over the next few years we will observe more milkweeds and fewer diseased caterpillars.

And the Monarchs which do survive will be progenitors of a slightly altered race of butterflies; a race which instinctively seeks more sheltered locations and more secure footholds when overwintering; a race more likely to survive the next similar winter storm with fewer losses.

The orange and black Monarch has guarded well the fire of life contained within its genes. It will not be extinguished. Each time the population has dwindled, the survivors have been those individuals which are more adapted to the conditions which threaten the species.

The Monarch Butterfly has been enduring winter storms since the close of the last Ice Age. It will spread from its winter refuge as far as its chosen food plant, the milkweed, will spread. If the forests of Altamirano are destroyed, it will seek refuge in the forests of Chincua or Picacho or Los Palomas.

If the mountains of Mexico are denuded by fire, drought, land clearing, or disease, the Monarch will spread from refuges in Florida or California or Guatemala or Yucatan. The butterfly that loses its way may survive to lead the next generation.

Next September, as you observe the "fragile" orange and black butterflies drifting southward through our mountain passes, consider the biotic strength of these delicate creatures. Consider the fire of life burning brightly within.