9 FARMERS’ BULLETIN 741. 
IMPORTANCE OF THE ALFALFA WEEVIL AS A PEST. 
This insect attacks Utah’s most important crop. Alfalfa furnishes 
80 per cent of the value of the hay and forage of the State, which in 
turn is 40 per cent of the value of all crops. The 1909 crop was 
worth nearly $6,000,000." 
About one-half of the annual yield is harvested in the first cutting 
and about one-third in the second. The damage to the first cutting 
ranges from slight depreciation of the quality of the hay to almost 
total loss, varying according to the rate of growth and the time of 
harvest; it may be estimated at 50 per cent. The damage to the 
second cutting, if no effort is made to prevent it, amounts to total 
loss. The menace to this State, there- 
fore, involves one-half the yield, worth 
$3,000,000. 
Besides the loss represented by these 
figures, there is a less tangible but equally 
serious effect due to the peculiar relation of 
alfalfa to western agriculture. Because of 
its ability to revive after prolonged drought, 
to produce abundant crops for many years 
Fic. 2.—The alfalfa weevil (Phytono- : : 
mus posticus): Larva. Much en- Without reseeding, and to furnish a nearly 
Ete neat) complete ration for live stock, it has a 
very great value for a region where the water supply is scanty, 
reseeding expensive and difficult, and live stock an important and 
increasing source of wealth. 
THE INFESTED DISTRICT. 
The infested district (fig. 3) reaches north from Salt Lake City to 
Rosette, Utah; Strevell, Malad City, and St. Charles, Idaho; and 
Cokeville and Granger, Wyo. It extends south to Moroni and Oasis, 
Utah. These points lie near the rim of a circle about 100 miles from 
Salt Lake City. Eastward the weevil has gone only about 50 miles 
to the Uinta Mountains and westward an equal distance to the Salt 
Lake Desert. 
SPREAD OF THE WEEVIL. 
Both the outline of the infested district and the history of the 
spread show an average seasonal advance of about 10 miles per year 
‘since 1904 or 1905, when the insect was discovered by farmers at Salt 
Lake City. ‘There are no isolated colonies distant from the main body, 
and there have been no long jumps in the movement. If wagons and 
railroad trains have carried weevils it has evidently been only for 
short distances. As has been predicted,? their spread has been 
largely by crawling and flight. The greatest progress has been along 
1 Thirteenth United States Census. 
2 Utah Agricultural College Extension Department Bulletin No. 1, 1909. 
