Yosemite National Park Lodgepole Needle Miner

The lodgepole needle miner ( Coleotechnites milleri ) is a rather unique insect, endemic to the upper Tuolumne and Merced River watersheds of Yosemite National Park and one small headwaters drainage of the San Joaquin River (Sierra National Forest). It lives mostly within the needles of lodgepole pine for two years, emerging as a little gray moth for a few weeks in July of odd-numbered years. This keeps any predators from becoming effective control agents and allows populations to escalate rapidly. While regular prehistoric outbreaks of lodgepole needle miners have been confirmed through dendrochronology, historic records document outbreaks from 1903 to 1921, 1933 to 1941, and 1947 to 1963.

Extensive stands of Ghost Forest and jackstrawed trees are still conspicuous throughout Yosemite National Park and the Sierra Nevada. Annual monitoring of lodgepole needle miner density began in 1966, and 28 permanent plots are scattered north of the Cathedral Range. The current outbreak began in 1973 and has been sweeping around the south side of the Cathedral Range, arriving at Sunrise High Sierra Camp in 2001. Lodgepole needle miner defoliation currently extends over approximately 40,000 acres, with nearly 10,000 acres of low to high mortality each year.

The lodgepole pine forest community is by far the largest vegetation type in the park, covering over 150,000 acres. While lightning fires are frequent in lodgepole pine communities, they usually remain small, with a resulting fire return interval at Yosemite estimated up to 764 years. Thus, fire suppression activities have had little influence upon species composition, structure, fuels, or natural processes. With natural fire playing such a small role in Sierra Nevada lodgepole pine forests in comparison with Rocky Mountain lodgepole pine forests, the lodgepole needle miner plays a key role in lodgepole pine forest succession and regeneration at Yosemite.

National Park Service Management Policies direct managers to allow native pests to function unimpeded except where control is desirable for specific cited reasons, including conserving plants in developed areas.

Additional Nature and Science Topics for Yosemite

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