in Clear lakes tributaries. Clear Lake is well-known among entomologists for the Clear Lake gnat (Chaoborus astictopus) and historical control efforts. This species of "phantom midge" (so called because the larvae are transparent and very difficult to see) measures less than long and resembles a tiny mosquito, but is non-biting. Clear Lake gnat hatches start anytime from March through June, depending on weather. Before pesticide use began in the 1940s (Refer to Rachel Carson's book Silent Spring, chapter 4), the gnat was so abundant around the lake in the summer that large piles of dead gnats appeared beneath streetlights, looking like dirty snow. The gnat swarms were so thick that people driving along the edge of the lake reported stopping every to clean the gnats off the windshields and headlights of their cars so they could see, and pedestrians tied kerchiefs over their faces to avoid inhaling the gnats. The rugged coastal mountains surrounding Clear Lake are covered with thick stands of oak-madrone forest, manzanita, sage shrubs, chaparral, grasses etc. Most common trees include blue oak, valley oak, interior live oak, pacific madrone, California scrub oak, plus very occasional coast redwoods and tanoak. Large stands of western white pine may be seen in the higher elevations. The heavy forestation and ruggedness of this part of California has helped prevent wholesale real estate development or farming. On the northeast slope of Mount Konocti is a heavily forested area known locally as the "Black Forest", because it never gets direct sunshine. This area has some Douglas fir in very heavy stands. History Archaeologists believe that the Clear Lake basin has been occupied by Native Americans for at least 11,000 years. (See: Post Pattern.) Evidence of this has been found at nearby Borax Lake and on Rattlesnake Island in the lake's south arm. Abundant fish, game and waterbirds made Clear Lake an oasis in the otherwise harsh conditions of Northern California's mountains. The native Clear Lake Hitch (Lavinia exilicauda), was once so abundant that millions of hitch clogged the lake's feeder streams in dry months. When the Spanish missionaries came to California, they found that thousands of Native Americans lived in the Clear Lake Basin, primarily Pomo, Yuki, and Wappo with some Lake Miwok. European settlers arrived, starting around 1845. Frequently they abused and exploited the native Pomo people. One of the most notorious incidents was the Bloody Island Massacre of spring 1850.