2 BULLETIN 932, TJ. S. DEPARTMENT OF AGRICULTURE. 



The data reported in the present publication fill an urgent need of 

 long standing for more complete and useful information regarding 

 the seasonal habits of the codling moth in the Grand Valley of Col- 

 orado. It should form a basis for constructive control measures for 

 the use of orchardists in this region. 



The plans for this investigation were made by the United States 

 Department of Agriculture. Bureau of Entomology, in cooperation 

 with the Colorado Agricultural Experiment Station. The work 

 was done under the general supervision of Dr. A. L. Quaintance. in 

 charge of deciduous fruit insect investigations. Bureau of Ento- 

 mology, and Prof. C. P. Gillette, director and entomologist of the 

 Colorado Agricultural Experiment Station. 



A field station was established at Grand Junction. Colo., in the 

 fall of 1914. by Mr. R, J. Fiske, of the Bureau of Entomology. The 

 senior author was placed in immediate charge of the work in 1915. 

 and was assisted during the year by Mr. E. R. Van Leeuwen. of the 

 Bureau of Entomology, and in 1916 by the junior author. Much 

 valuable information was given from time to time by Messrs. George 

 M. List and Claude TTakeland. of the entomological department of 

 the Colorado Agricultural Experiment Station. 



The general character of the work in the Grand Valley was quite 

 similar to that of the codling-moth investigations conducted by the 

 Bureau of Entomology in several other fruit districts, but it was 

 carried out on a somewhat larger scale and includes certain phases 

 of the life history and habits of the codling moth not hitherto 

 reported. 



THE GRAND VALLEY OF COLORADO. 



LOCATION AND DESCRIPTION. 



The Grand Valley of Colorado is located in Mesa County, on the 

 western slope of the Rocky Mountains, is about 32 miles in length, 

 and has an extreme width of 5 miles. It comprises nearly 75.000 

 acres of land, about one-fifth of which is .planted to fruit. At the 

 time of these investigations there were approximately 10,000 acres 

 of apples and about 2.500 acres of pears, while the remainder of the 

 fruited area was devoted chiefly to peaches, plums, cherries, apri- 

 cots, and bush fruits. The great majority of the orchards, of which 

 the one shown in Plate II is a good example, were planted north of the 

 Grand River, which flows through the entire length of the valley. 



TOPOGRAPHY AND ELEVATION. 



The valley is comparatively level, with the exception of a few 

 elevations known locally as the '" Fruit Ridges." The fruit district 

 of Orchard Mesa, while higher than most other parts of the valley, 

 is typical tableland. The general elevation of the Grand Valley 



