INSECT ENEMIES OF WESTERN FORESTS 109 



branch excessively. This bud moth is also reported from Engel- 

 mann spruce. 



The larch bud moth (Zeiraphera griseana (Hiibner)), another 

 European species, has recently caused heavy defoliation of larch 

 and white fir over 86,000 acres in eastern Washington. The larvae 

 feed on the tender new growth, causing damage similar to that of 

 the preceding species. It has also been reported from foliage of 

 Engelmann spruce and Douglas-fir and ranges through Oregon, 

 Washington, British Columbia, Idaho, and Montana. The moths 

 have grayish-white wings splotched with dark brown and black 

 patches and a wing expanse of y 2 to % inch. 



There are a large number of other budmoths and leaf rollers 

 that infest the buds and young, tender leaves of various broad- 

 leaved trees and shrubs. This damage is often serious in orchards 

 but seldom is important in the forest, therefore no attempt is made 

 to discuss them. 



NEEDLE MINERS 



Some leaf-eating insects have the habit of feeding internally 

 on coniferous needles and thus protecting themselves within a 

 thin, leafy covering. These are called needle miners. A great many 

 of them cause only an insignificant amount of damage, but a few, 

 such as the lodgepole needle miner, may defoliate extensive areas 

 and contribute to the destruction of the timber cover on entire 

 watersheds, as has happened in parts of the Yosemite National 

 Park in California. 



Outbreaks of needle miners are eventually brought under con- 

 trol by native parasites and climatic conditions, so control meas- 

 ures are seldom needed. Direct control through the use of sprays 

 or dusts is difficult to obtain, since the insects are not easily 

 reached. Experiments by Yuill (163) indicated that light, pene- 

 trating oil sprays to which nicotine had been added offered 

 promise of being effective for the protection of valuable trees. 

 More recent experiments have shown that benzene hexachloride is 

 even more effective than nicotine. A spray containing 0.1 pound of 

 the essentially pure gamma isomer, 0.06 gallon of auxiliary sol- 

 vent, and 0.94 gallon of fuel oil can be applied at the rate of 1 

 gallon per acre. 



The lodgepole needle miner (Recurvaria milleri Busck.) (129) 

 (fig. 47) is the best representative of this group in the West. As 

 its name implies, it mines the needles of lodgepole pine and has de- 

 foliated extensive areas of lodgepole pine in California, Idaho, 

 Montana, and Alberta, Canada. It has also been found mining 

 needles of western white pine and Jeffrey pine in epidemic areas. 

 Outbreaks in Yosemite National Park, where it was first discov- 

 ered, have so weakened the trees that they readily succumbed to 

 attacks of the mountain pine beetle. Farther north its outbreaks 

 have caused much less timber mortality. The adults are very small 

 white or grayish moths only about y 2 inch long. The caterpillars 

 are very small greenish worms with black heads. This species has 

 a 2-year life cycle, the moths flying in alternate years — even-num- 

 bered years in Canada and odd-numbered years in California. The 



