A Winning Combination

Humans suffer staggering economic and medical* losses due to insects. Outbreaks of billions of locusts in Africa are only one example. In the western United States and Canada, an outbreak of mountain pine beetles in the 1980s and 1990s killed pines on huge acreages, and the 1973 to 1985 outbreak of spruce budworm in fir/spruce forests killed millions of conifer trees. Since its introduction in the 1920s, a fungus that causes Dutch elm disease, mainly transmitted by European bark beetles, has virtually obliterated American elm trees in North America.

In 2004, another alien invader, the emerald ash borer, a beetle, threatens to decimate the ash trees of North America. These examples serve to remind us of our ceaseless struggle with the dominant group of animals on earth today: insects. Insects far outnumber all other species of animals in the world combined, and numbers of individuals are equally enormous. Some scientists have estimated that there are 200 million insects for every single human alive today! Insects have an unmatched ability to adapt to all land environments and to virtually all climates.

Insects evolved wings and invaded the air 250 million years before flying reptiles, birds, or mammals. Many have exploited freshwater and saltwater (shoreline) habitats, where they are now widely prevalent; only in the seas are insects nonexistent, except for those pelagic species existing on the ocean's surface.

How can we account for the enormous numbers of these creatures? In common with other arthropods, insects have a combination of valuable structural and physiological adaptations, including a versatile exoskeleton, segmentation, an efficient respiratory system, and highly developed sensory organs. In addition, insects have a waterproofed cuticle, and many have evolved extraordinary abilities to survive adverse environmental conditions.