Hibernation of the corn earworm in the central and northeastern parts of the United States Page: 7
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HIBERNATION OF THE CORN EARWORM 7
were stocked with larvae was reduced to 13, including two new
locations, Prosser and Walla Walla, Wash. Pupal survival occurred
at 9 points. Cages installed at Orleans, Ind., during 3 seasons were
not examined for pupal survival.
Moth emergence in the cages extended from the second week in
May to the last week in June. The earliest record of emergence
was between May 8 and 10 at Charleston, Mo. Observations as to
the time of first appearance of eggs, larvae, or adults in the field
indicate that adults emerge at approximately the same time under
either field or cage conditions.
It would appear from a study of soil temperatures at the various
stations that lethal temperatures alone do not explain the mortality
at the more northern stations, although longer duration of the low
temperatures at those stations may aid in bringing about the mortality.
Factors which, taken in conjunction with low temperatures, increase
the mortality rate are the moisture content of the soil and heaving
through action of frost.
CLIMATIC AND SOIL FACTORS
As is shown in tables 1 and 2 a wide range in climatic and soil
factors known to affect hibernation is represented. The data can,
perhaps, best be interpreted by making some comparisons of these
factors. For this purpose the soil temperatures and precipitation
data for five key localities were studied. The important figures from
this study are given in table 3.
TABLE 3.-Summary of soil temperatures, rainfall, and survival of the corn earworm
at five key locations, 1935-36 to 1938-39, inclusive
Depth Minimum Periods of Total
Period Locality below tempera- freezing Nov.- survival emergence
surface ture or below .
Apr.
Inches F. Days Inches Percent Percent
Arlington, Va-------- 4 22.5 35 22.2 0.5 0
Carlisle, Pa _ .-------- 4 28 83 22.5 0 0
1935-1936 _ Toledo, Ohio----------- 4 20 ------- 12.0 0 0
I rbana. Ill ---- ---------- -------- -----
lManhattan, Kans----- 4 16 58 6.1 0 0
Arlington, Va--------- 3 29 8 25.5 24.5 2. 3
Carlisle, Pa--------- - 4 29 51 24.7 13.5 0
1936-1937_ Toledo, Ohio ----- - 4 18 155 17.0 0 0
Urbana, I11 -------- 4 22 79 21.4 0 0
Manhattan, Kans 1-- ' 212 16 73 6. 2 0 0
Arlington, Va---- 3 32 1 13.5 29.5 .75
Carlisle, Pa ------ 4 29 26 14.9 22.5 0
1937-1938 -- Toledo, Ohio---------- 4 17 145 14.4 0 0
Urbana, Ill ---------- 4 22 92 18.0 0 0
Manhattan, Kans 14 26 44 5.5 0 0
Arlington, Va---. .-- 3 32 1 17.3 41.5 3 1.
Carlisle, Pa ---- - 4 42 0 18.8 24.0 0
1938-1939.-_ Toledo, Ohio ---------- 26 36 0-136 13.2 0 0
Uirbana, Ill ---------- 4 26 52 15.8 0 0
Manhattan, Kans 2. 18 73 6.5 2.0 6.0
1 Minimum temperature at 4-inch level was 2 higher than at the 234-inch level during 1935-36 and 100
higher during 1937-38.
2 Sand covered by corn shock had 2 days of freezing temperature or below; sand, uncovered, had none,
and sandy loam, covered, had 136 days with temperature at or below freezing.
3 ADDroximate.
Manhattan, Kans., Urbana, Ill., Toledo, Ohio, Carlisle, Pa., and
Arlington Farm, Va., were selected for this study since those localities
represent the extremes in climatic conditions as well as in pupal sur
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Blanchard, R. A. Hibernation of the corn earworm in the central and northeastern parts of the United States, book, December 1942; Washington D.C.. (https://digital.library.unt.edu/ark:/67531/metadc5968/m1/7/: accessed April 19, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.