482 
Journal of Agricultural Research 
Vol. XXX, No. 5 
“Later in the season when the 
spring rains have ceased, the fungus 
seems to be restricted to fields which 
are generously irrigated and have a 
heavy, close stand of alfalfa. One 
such field was examined on July 29 and 
28 weevils with a pure growth of 
Sporotrichum were picked up in a 
short time. Such mortality at this 
late date is of slight importance, how¬ 
ever, as this is the time when the over¬ 
wintered adults are dying off naturally. 
Yet it is worthy of note that this field 
for which a generous water supply was 
available and which was therefore 
lavishly irrigated has never been seri¬ 
ously injured by the weevil, at least 
so the rancher informed me, and I was 
inclined to believe him, as it was cer¬ 
tainly unusual for a Utah farmer to 
deny injury from the weevil . . f* 
The above statements give a basis 
for determining the optimum condi¬ 
tions for fungous growth on the alfalfa 
weevil at Salt Lake City. The normal 
temperature for April is 50° F., and the 
normal April rainfall about 2 inches. 
So far as the production of a favorable 
humidity is concerned, this would be 
roughly equivalent to a monthly rain¬ 
fall of 23^ inches at 60° F., or of 3 
inches at 70° F. (#, p . 65). On this 
assumption, we can estimate the 
climatic suitability of any region for 
fungous growth by studying its ap¬ 
proach to this curve, and we can tell 
whether or not the fungus Sporo¬ 
trichum globuliferum will be an economic 
factor. This point is used frequently in 
studing the distribution of the alfalfa 
weevil in America. 
Summary of Climatic Relations of 
Phytonomus Posticus in America 
The following points of importance 
in this study have been found in this 
survey of American literature: 
The limiting temperatures are about 
0° F. and 120° F. 
Warm, dry spring weather is essential 
for the rapid multiplication of the 
weevil. Such weather shortens the 
season of oviposition and produces a 
maximum number of larvae working 
simultaneously. 
The damage decreases with an in¬ 
crease in altitude. An increase in 
altitude in this region is equivalent to a 
shortening of the growing season plus 
an increase in precipitation. 
Cold, damp spring weather hke that 
of Montana, as opposed to the hot, 
dry spring weather of the Great Basin, 
not only retards the rate of develop¬ 
ment of the weevil itself, but is favor¬ 
able to the increase of fungous enemies, 
which aid in checking the damage. 
THE CLIMATIC ECOLOGY OF 
PHYTONOMUS POSTICUS IN THE 
OLD WORLD 
The Old World distribution of the 
alfalfa weevil is given by Titus (18) as 
all of Europe, southern Siberia, Turk¬ 
estan, Asia Minor, Persia, Arabia, 
north coast of Africa, Madeira, and 
Canary Islands. He records out¬ 
breaks of this or some very closely 
related species in southern France, 
Italy, and southern Russia. 
This is a very general statement from 
which to develop the climatic relations 
of this insect, so the writer has used a 
second method of determining the eco¬ 
nomic distribution. A search was in¬ 
stituted through two abstracting peri¬ 
odicals, the Review of Applied Ento¬ 
mology, Series A, and the International 
Review of the Science and Practice 
of Agriculture. The material is pre¬ 
sented below in three categories. 
“ Mention ’* indicates a mere mention 
of the insect in a general list of pests, 
with nothing to show that any damage 
was done by it. “Minor pest” indi¬ 
cates that some slight damage was done 
in the year indicated. “Major pest” 
indicates a serious outbreak, recorded 
in one or several extended articles. 
Many of the articles recorded below are 
not important in the further study of 
the weevil, so the original sources are 
not quoted. 
Economic Distribution of P. 
Posticus 
Major pest: 
Southern France. —1914. Controlled to some 
extent by a fungus, Entomophthora sphaero- 
sperma. 
Italy. —No recent references. Titus (13) gives 
the following dates of outbreaks: 1884, 1890, 
1909, 1910, 1911. 
Turkestan— 1913. In connection with a paper 
on the utility of the Wagtail, an insectivorous 
bird, the alfalfa weevil is noted as a very 
serious pest. It does a large amount of dam¬ 
age, there being no natural control for it ex¬ 
cept birds. 
-. 1914. Listed as a major pest in the 
valley of Isfara (Ferghana) this year. 
Minor pest: 
Sweden. —1912. 
Denmark— 1916. Districts of Lolland-Forster 
and Naestvod, controlled by fungus. 
Germany. —1922. 
Southern Russia. —Governments of Kiev, Mos¬ 
cow, and Kherson. No dates given. 
Transcaucasia. —Districts of Tiflis and Erivan. 
Was a pest in these regions in 1916-17. 
Mention: 
Denmark. —1918, 1919, 1920. 
Russia. —Moscow. No dates given. 
Astrachan. —Mentioned in a list of pests of 
alfalfa. 
Reeves (8, p. ISO) makes the follow¬ 
ing statement, which explains the 
scarcity of serious outbreaks in Italy. 
. . . “There is a possibility that in a 
different climate from that of Utah 
