480 Journal of Agricultural Research voi. xxx, no. 5 
—--—- 1 -- 
summer is rather cool and cloudy, they 
will go into hibernation earlier, and 
apparently more of them pass through 
the winter successfully. In the higher 
mountain valleys the weevils become 
adult later in the summer and enter 
into hibernation earlier.” 
Apparently the rate of oviposition is 
closely related to temperature. Parks 
(7) has published detailed information 
upon the relation of temperature tg 
oviposition, and it is evident from his 
chart (7, p. 4%0) that there is very 
little oviposition until the mean daily 
temperature reaches about 50° F. 
Titus ( 14 , p . 11.8) makes the following 
statement, which is substantiated by 
Parks: 
“The length of the egg-laying period 
each year naturally has a decided effect 
on the length of time that appreciable 
injury will occur to the crop for that 
year. Warm, dry, spring weather 
appears to be conducive to rapid egg 
laying, and thus many more larvae are 
feeding on the alfalfa at any, one time 
than when tjie egg-laying period is 
extended over several months. Under 
these conditions more larvae come to 
maturity and the damage to the crop 
is more severe, since so many worms 
are present that there is little chance 
for the plant to recuperate. On the 
other hand, a slow cold spring and 
summer means that egg laying will con¬ 
tinue for many weeks, and though 
probably as many larvae actually feed 
throughout the season, the damage to 
the crop harvested is not so great, the 
plant continually having opportunity 
to develop new buds and leaves. This 
readily explains the apparent decrease 
in injury in infested regions in 1912 as 
compared with the loss in 1911 in the 
same sections of the State.” 
The following table shows conditions 
in the spring months at Salt Lake City 
in 1911 and 1912: 
Month 
Mean 
tempera¬ 
ture 
Total 
precipita¬ 
tion 
1911 
1912 
1911 
1912 
°F. 
0 j? 
Inches 
Inches 
March.___ 
44.4 
40.6 
2.04 
3.48 
April____ 
47.9 
46.8 
1.65 
2.34 
May-- 
57.2 
55.8 
1.84 
1. 75 
Means and totals.. 
49.8 
47.5 
5.53 
7*57 
These figures, which substantiate the 
above statement so far as climatic con-, 
ditions are concerned, are taken from 
the Annual Meteorological Summary 
(16) for Salt Lake City for 1921. 
The following notes regarding the 
influence of altitude upon damage are 
of particular interest when considering 
temperature. 
Ball (1, p. 144)'- “As it passes out of 
the warm sections, around Utah and 
Salt Lake .Valleys, its damage has 
become less and less until, in quite a 
number of districts, it is pretty hard to 
convince the farmers that they have it 
at all.” 
Titus (15, pp. 133-134 ): “In no 
place in Idaho is it kpown to be doing 
damage. Weevils are so*few in most 
places that you have to search for 
them.” 
This statement was made in 1916, 
when the weevil was confined to the 
higher parts of southeastern Idaho. 
Reeves et al. (9, p. 88 ): “. . . There 
is hope also that the pest will not prove 
equally injurious under all circum¬ 
stances. It is mudh less harmful in 
Europe than in America, owing appa¬ 
rently to climatic and industrial con¬ 
ditions, and it multiplies more slowly 
and does less damage in the higher 
altitudes, in Utah and Wyoming than 
in the lower valleys.” 
In considering the migrations of the 
adult beetles, the statements below may 
be quoted. 
Reeves et al (9) p. 87): “There is .no 
evidence that the weevils ever fly for 
the purpose of seeking fields of alfalfa, 
either new or previously infested, or to 
find hibernation quarters. The most 
plausible theory is that their flight is 
caused by a rise in temperature, as are 
many activities of the lower animals. 
So far as can be learned, this flight is at 
random. It takes some of the weevils 
into new fields.” And, again (9, pp. 
92-93): “The heat of the soil is also 
probably an important cause of that in¬ 
crease in the activity of the adults, 
called the summer flight, which is 
greatest during the dry, hot weather be¬ 
ginning in June and ending in August. 
This flight accounts for the presence of 
many adults in grassy places and or¬ 
chards, where they alight and find pro¬ 
tection from the heat ... The summer 
flight is not a general movement of the 
weevils from the fields to seek more 
suitable hibernation places elsewhere. 
There is no such movement, and vir¬ 
tually all of the weevils spend the win¬ 
ter in the fields.” 
Very little was found regarding the 
minimum fatal temperature. The re¬ 
mark of Reeves (9, p. 91), quoted be¬ 
low, is of importance: “Many weevils 
die in the fields during zero weather, but 
milder temperatures seem to have little 
effect upon them.” 
