- 2 - 
In addition to fenugreek and alfalfa, Hypera brunneipennis was 
found to be feeding on bur-clover (Medicago hispid a Gaertn.), hubam (annual 
form of Mel i lotus alba Desr.), and sourclover (Me lilo tus indica L.) The 
sourclover is of general occurrence on uncultivated areas in the Yuma 
Valley. Sufficient feeding occurred on this plant to be classed as eccncm- 
ic damage. Bur-clover in one small field was also heavily attacked. Noth- 
ing definite concerning the suitability of alfalfa as a host was determined 
since the first and a portion of the second crop had been harvested prior 
to the discovery of the weevil. Consequently, the economic importance of 
the weevil as a pest of alfalfa could not be evaluated until the advent of 
another larval brood. 
A preliminary investigation during the last days of April 1939 
showed that larvae were scarce and mostly mature, cocoons containing pupae 
were fairly numerous, and adults were extremely abundant in the few heavily 
infested spots. It was thus apparent that a brood was almost completed 
and that little could be determined until another appeared. The immediate 
consideration was whether or not this would occur immediately and endanger 
the valuable summer alfalfa seed crop. Subsequent discovery that adults 
were apparently aestivating, together with studies shewing the sexual im- 
maturity of both males and females, appeared to indicate a period of inac- 
tivity which might possibly extend thjrcugh the extreme summer heat into early 
fall. Nevertheless, it was decided to continue the studies under the super- 
vision of J. C. Hamlin as a part of the Bureau's alfalfa weevil investiga- 
tions, and for this purpose a substation of the Salt Lake City, Utah, office 
of the Alfalfa Weevil Investigation was established at Yuma during June 1939. 
This paper is an account of the findings during the first year. 
EXTENT OF INFESTATION 
Scouting in 1939 indicated that Hypera brunneipennis was confined to 
the Yuma Reclamation Project, mcstly to the northeast portion of the Yuma 
Valley, Yuma County, Ariz. , in an area approximately 8 miles long and 2 miles 
wide. A small extension of this area was found immediately north of Yuma 
on the Fort Yuma Indian Reservation near Winterhaven, Imperial County Calif 
Further scouting outward from these limits and in other suspected areas of 
California and Arizona gave negative results. However, the near-completion 
of the larval brood cast doubt on the validity of the survey. 
In 1940, as soon as the insect resumed activity in the fields a 
thorough survey was conducted by the Bureau of Entomology and Plant Quaran- 
tine in cooperation with the Arizona State Entomologist's office and the 
California State Department of Agriculture. Preliminary scouting during 
January and February resulted in corsiderable extension of the area known to 
be infested in the Yuma Valley and in the California portion of the Yuma 
Reclamation Project. Two small infestations were also discovered in the Gila 
Valley, northeast and east of Yuma. All these infestations, however 
within a radius of about 9 miles from the city. 
were 
