BUEEAU OF ENTOMOLOGY. 223 



advances is numerically weak and little or no damage occurs, but if 

 the natural enemies fail to exercise control in southern Texas and 

 central Florida, the species becomes abundant and starts on its 

 spread to the northward. The evidence is now conclusive that 

 measures of practical control inaugurated in the Brownsville section of 

 Texas and in central Florida exert an influence in preventing destruc- 

 tion throughout the territory to the northward. 



Alfalfa weevil. — ^The work on the alfalfa weevil consisted largely 

 of experiments in control by the use of arsenicals, and in the estab- 

 hshment of European parasites. The results from the application of 

 arsenicals were very satisfactory and it now appears that the prin- 

 cipal work to be done on this topic is in the way of reducing the 

 expense of the operation. Very careful attention was given to the 

 possibility of the poisoning of stock, but it appears that the work can 

 be done in such a way as to eliminate all danger. Progress was made 

 in determining methods of pasturing which wm also control the weevil. 

 A system of inclosing sections of alfalfa fields with temporary fences 

 and pasturing the live stock in one of these sections after another 

 until the whole field is grazed was found to be effective, but certain 

 questions relating to farm management have arisen in this connection 

 which will require further attention. The European Canidiella para- 

 site appears to have become fully established at five points in Utah. 

 It is believed that this species will eventually exert considerable con- 

 trol over the alfalfa weevil. 



INVESTIGATIONS OF INSECTS AFFECTING FORESTS AND FOREST 



PRODUCTS. 



The work on insects affecting forest growth and crude and finished 

 products has been continued under the supervision of Dr. A. D. 

 Hopkins. Some of the subjects which received special attention 

 were as follows: Insects affecting forest-tree seeds; damage to forest 

 reproduction by pitch moths ; relation of latitude, longitude, altitude, 

 and local conditions to the distribution of forest-insect species, sea- 

 sonal histories, and methods of control; relation of injuries by light- 

 ning to subsequent injuries to the forest by tree-killing insects; 

 insects injurious to forest products; economic study of beneficial 

 insects, and insect-control instructions and demonstrations in the 

 national parks. 



Insect damage to cones and seeds of Pacific Coast conifees. — 

 Investigations show that insects cause practically an entire failure of 

 the seed crop of conifers in certain localities of the Pacific coast in a 

 single season. Among insects of this class are beetles which cause 

 "blighted cones" and in some years the destruction or a great reduc- 

 tion over extensive areas of the seed crop of the two principal timber 

 trees of the Pacific coast region. With the information now made 

 available through publications, however, seed collectors will be able 

 to find locahties where full crops may be secured. 



Sequoia pitch moth. — It has been found that the Sequoia pitch 

 moth is a menace to the reproduction pine m western Montana, espe- 

 cially m a certain area of more than 90,000 acres, but that it is prac- 

 ticable to control it by removing the conspicuous pitch masses on the 

 young growmg trees and destroying the young larvae. 



