We have talked about monarch butterflies before. The orange and black butterflies are often used in school lessons about insect ecology. Monarch caterpillars forage exclusively on milkweed; in the process they acquire foul-tasting chemicals that ward off predators. In late summer, monarchs living in the Eastern U.S. migrate to overwintering grounds in Mexico.
Weeds are the bane of many a gardener's or landscaper's existence. They sprout up, uncontrolled and unwelcome, and must be tediously managed time and again. But some weeds are more than a nuisance – they rise to the level of a public health hazard. Such is the case with giant hogweed.
Hemlock is a "foundation" tree species in eastern forests and its presence defines the properties of a unique ecosystem that is presently declining due to the introduction and spread of an invasive insect, the hemlock woolly adelgid.
Earthworms effect microbial nitrogen cycling and ecosystem nitrogen retention. Earthworm invasion of north temperate forests will have large consequences for nutrient retention and uptake in these ecosystems.