Monarch Butterflies at Risk in N. America
B. McPherson Let's make sure future generations have a chance to witness this. For many N. Americans the return of the monarch butterflies is a sure sign that summer is here. These special butterflies with their cheery black and orange coloring are unique in their migratory habits. Because the monarchs are vulnerable to cold, they fly south in the autumn to winter in Mexico and California. They gather in the thousands in trees and enter a state of reduced metabolic activity, living on their fat reserves. The epic journey of the monarchs is under siege. In both the eastern and western populations, butterfly counts have plummeted in California and Mexico. The November 1997 count in California was 1,250,000 per site. In 2009 there was an average of 1250 at each site. In There are several factors that are thought to have affected the numbers. Lack of Food Monarch butterflies’ life cycle includes a caterpillar stage. The caterpillar must feed on milkweed plants or d...