Our Window on Nature

Just about everybody likes to eat insects - mammals, birds, amphibians, reptiles, spiders, other insects, and even some humans. Over in Great Britain, a scientist with time on his hands calculated that the country’s spiders consume enough insects each year to total the combined weight of the entire human population. And that’s just the spiders. Why, then, are there so many insects left over?

“Bug-ologists” point to several reasons why insects are nature’s most successful creatures. For one thing, insects breed in astronomical numbers. They can afford to lose a high percentage of their population to predation. And for another, insects have highly sophisticated strategies for self-defense. It’s these defense strategies that we’ll be investigating here - house building, chemical warfare, warning coloration, mimicry, and camouflage - because they are strategies that you’ll be able to view first-hand as you travel. First the architects. (Read the rest …)

Just how far can a butterfly fly - assuming it has the urge? Down the block? Across town? All the way to the county line? Much, much farther if you happen to be a monarch - up to 3,000 miles.

Like Snowbirds, they fly south, hundreds of millions of wings filling the air. We’ve watched them flutter along the Massachusetts shoreline, and we’ve seen pine trees hung with living lace where they have settled to roost overnight. We’ve accompanied them across the Nevada desert, asking why they couldn’t find a less arid route. It’s little wonder that the monarch migration is one of the world’s great natural events.

Actually, the monarch is the only butterfly to make this massive, species-wide migration. Others may do a certain amount of moving about in search of food, but no one else in the insect world follows as predictable a path to as certain a location. Why do it then?

What follows is still speculation, but it’s informed speculation by lepidopterist Lincoln Brower, zoology professor at the University of Florida. He points out that most butterflies in the subfamily Danaiinae (to which the monarch belongs) are tropical, and cannot survive a cold winter - not as eggs, larvae, pupae, or adults.

On the other hand, monarchs eat only milkweed, and it’s a particularly widespread plant farther north. Brower suggests that back in the glacial epoch monarchs began migrating farther and farther north to take advantage of that food supply, without cutting ties to their southern home. (Read the rest …)