My Doll Blog

Green invaders are taking over America. Nope, not invaders from space. Plants. You might not think of plants as dangerous, but in this case they are threatening nature's delicate food web.

The invaders are plants from other countries brought here to make gardens and yards look pretty. Ever since people started to arrive on America's shores, they've carried along trees, flowers, and vegetables from other places.

Now there are so many of those plants, they are crowding out the native plants that have lived here since before human settlers arrived.

And that's a problem, says Dr. Doug Tallamy. He's an entomologist (an insect expert) at the University of Delaware. He explains that almost all the plant-eating insects in the United States—90% of them—are specialized. That means they eat only certain plants.

Pretty orange and black monarch butterflies, for example, can only dine on one plant: milkweed. If people cut down milkweed and replace it with something else, the butterflies starve, because their bodies cannot accept any other food.

But the trouble doesn't stop there, it goes right across the food web. When insects can't get the right plants to eat and they die off, then the birds don't have enough bugs for their meals. Tallamy points out that almost all migrating birds depend on insects to feed their young.