California is home to an incredibly diverse biota. In addition to over 30,000 species of insects, California boasts 563 birds, 96 reptiles, 190 mammals and well over 5000 species of plants. And the numbers only tell part of the story. The geographical diversity which is responsible for this great biological diversity has also helped to preserve many unusual species, for example, giant redwoods and California Condors. Many unique insects are also restricted almost entirely to California. Rain beetles, Timema walking sticks, and Diphyllostoma beetles, to name a very few, all represent ancient lineages which are centered in California today.
However, California is also home to an incredible diversity of humans, over 30 million of us and counting. As we occupy more and more space and demand more and more resources, we are disrupting the delicate systems which maintain the state's great biotic diversity. Some bioregions have almost completely succumbed to the pressures of development, such as the Central Valley, historically a mosaic of marshes, grasslands, and riparian woodland.
Human development has already significantly impacted California's insect biodiversity as evidenced not only by the 20 insects currently listed as threatened or endangered by the United States Fish and Wildlife Service, but also by the nearly 150 additional species which have been proposed for listing but which are still in review. Though this WWW site concentrates primarily on existing threats to California's insects, it must be emphasized that there may be groups in more serious trouble than the insects. For example, most of California's 60 fish species are listed or are proposed for listing. Clearly California's biodiversity is being seriously impacted. The species treatments in this site attempt to call attention to habitat degradation which may be responsible for the decline of each insect. The insects are merely indicators telling us that something is wrong. We should pay attention.