50 MISC. PUBLICATION 273, U.S. DEPT. OF AGRICULTURE 



larvae bore into terminals or branches killing them or patches of 

 bark. The bark on some trees may be honeycombed with tunnels 

 for several feet. The winter is passed as larvae or eggs, and moths 

 emerge the following summer. 



PINE TIP MOTHS 



The pine tip moths, belonging to the genus Rhyacionia, may 

 cause considerable damage to new leaders and shoots of young 

 pine in localities of heavy infestation, especially in plantations or 

 on cut-over lands where trees are openly spaced and growing on 

 sunny exposures. Trees from seedling size up to a height of about 

 25 feet are the most susceptible to injury. The small moths are 

 yellow, gray, or reddish brown. They lay their eggs on the pine 

 needles, and the young caterpillars start feeding at the tips of 

 shoots, burrowing into the buds and down into the new growth. 

 Their work is characterized by a resinous exudation at the point 

 of attack, but they do not form a pitch nodule on the stem. Though 

 trees are seldom killed, they are often deformed or forked, and 

 height growth is retarded. Several species have been described 

 from the Western States, where they normally work on the tips 

 of young forest trees. Two species are particularly destructive in 

 the pine plantations of the Nebraska National Forest. 



The western pine tip moth (Rhyacionia frustrana bushnelli 

 (Busck) (7, UO, 63, 15U) (fig. 19) causes some damage to seedlings 

 and saplings in its native range in the Black Hills, the Lake States, 

 and northwestern Nebraska, but has done serious damage where 

 introduced in the isolated pine plantations of the Nebraska Na- 

 tional Forest. In the ponderosa pine plantations of this forest about 

 90 percent of the leaders have been injured annually for many 

 years by this tip moth. The adult moths are small, with a wing 

 spread of about % inch. The front wings are mottled with yellow- 

 ish gray and reddish brown. The larvae are yellowish and when 

 full grown are nearly y 2 inch long. A single generation occurs in 

 the Black Hills, the moths flying late in May and early in June 

 to lay their eggs on the pine needles, and the larvae feeding during 

 June and July. In Nebraska two generations develop annually, the 

 moths flying in April and May and again late in June and early 

 in July. The winter is passed in the pupal stage in cocoons spun 

 by the larvae in the litter or soil. 



The southwestern pine tip moth (Rhyacionia neomexicana 

 (Dyar) ) has caused considerable injury to ponderosa pine seed- 

 lings and saplings at various places in the Southwest and is be- 

 coming a serious pest in the Nebraska National Forest plantations. 

 It is known to occur in New Mexico, Arizona, southern and eastern 

 Colorado, the Black Hills, and Nebraska. The moths measure about 

 1 inch in wing spread. The base of the front wings is dark gray 

 and the outer third reddish orange. The reddish larvae, when full 

 grown, are nearly % inch long. There is but one generation an- 

 nually. The moths fly in April and May in most localities, but in 

 the Black Hills in the latter part of May and early in June. The 

 full-grown larvae leave the tips during July and spin cocoons, 

 usually in the bark crevices on the base of the tree below the litter. 



