134 BULLETIN 1105, U. S. DEPARTMENT OF AGRICULTURE. 



Several insects are responsible for serious injury to western yellow 

 pine reproduction. Of these, a white grub, or May beetle larva 

 (Listrochelus falsus Lee), and two tip moths (Evetria bushnelli 

 Busck and E. neomexicana Dyar) are most destructive. Since no 

 special studies of these insects have been made with reference to 

 their control in the forest, there is little to add to the account of 

 their activities given in previous publications (18). It is sufficient 

 to state that the white grub devours the roots of seedlings up to 

 10 years of age, while the tip moth kills the terminal shoots of 

 seedlings and saplings. Plantations have shown as high as 90 

 per cent of the plants killed by the white grub in a period of 

 three years. In a broadcast sowing experiment, large patches 

 were cleared of seedlings in their third and fourth years by 

 this grub, and at the present writing fresh work is in evidence, 

 the seedlings now being 7 years old. Almost invariably where 

 examinations have been made in the yellow pine type in the vicin- 

 ity of Flagstaff, the soil is infested with white grubs. Since this 

 is a common pest in agricultural regions the world over, its range 

 in the yellow pine forests of the Southwest is probably not lim- 

 ited to any particular section. The tip moth, on the other hand, 

 confines its activities mainly to the lower altitudes, doing its worst 

 damage near the lower limits of the yellow pine type. Plants at- 

 tacked by the white grub are usually killed, but a large proportion 

 of those attacked by the tip moth recover. No practical remedy for 

 either the white grub or the tip moth has been found. 



RODENTS. 



Seed-eating rodents, such as mice and chipmunks, are an im- 

 portant factor in yellow pine reproduction. In seasons of light 

 seed production they apparently consume the great bulk of the crop. 

 The activities of these pests are undoubtedly the greatest factor in 

 accounting for the failure of broadcast sowing. Birds are also 

 known to pick up seeds, but since hard-shelled seeds usually pass 

 through the alimentary canal of birds without injury, the effect 

 may be merely to transport the seed from one place to another. 

 Birds are known to aid materially in the dissemination and germina- 

 tion of junipers, and it is likely that they play a similar role in 

 relation to the pine. The only observed instance of positive damage 

 by birds is in the case of the junco (J unco dorsalis), which plucks 

 the seed coats and cotyledons from young seedlings and even cuts 

 down the entire plant. The beneficial effects of birds as a class in 



20 Specific determinations made by the Bureau of Entomology, United States Depart- 

 ment of Agriculture. 



