I 
- 17 - 
The mean depth during October 1937 and October 1938 was approximately 
the same, but during November and December 1938 the mean depth was greater 
than in the same months of 1937. This additional depth in 1938 is thought 
to have been due to the lack of rainfall which prevented eggs from hatching, 
thus making fewer small larvae to be found in the upper part of the soil. 
The larvae move nearer the surface during March and April to feed on plant 
roots and complete their development. The mean depth was greatest during 
June, because many of the larvae in the upper part of the soil pupated and 
none hatched at that time. During the 15-month period October 1937 to 
December 1938 from 55 to 85 percent of the larvae have been found in the 
upper 6 inches of soil. The percentage of the total number of larvae in 
the upper 12 inches during this same period ranged from 89.8 to 100 percent. 
In only one month, March, were all the larvae found in the upper 12 inches. 
Although diggings have been made to much greater depths, larvae have not 
been found beyond the layer of soil 21 to 24 inches below the surface. 
Larval population . — During November and December 1937 and in November 
1938 larval-population counts were made in a number of fields throughout 
the Florala area. In the fall of 1937 three cores, approximately 4 inches 
in diameter and 12 inches deep, were taken with a soil sampler in each of 
5 places in each field, and in the fall of 1938 three cores of approximately 
the same size were taken in each of 9 places in each field. The washing 
method described above was used for determining the number of larvae present 
in these samples. The results have been grouped according to the crop grown 
each year and are presented in table 9. 
Table 9. — Larval populations of the white-fringed beetle in the fall of 
1937 and 1938 in fields planted to various crops, Florala, Ala. 
Average number of larvae 
per square yard 
1937 1938 
147 44 
41 171 
283 166 
44 
198 45 
Average 184 86 
Forty-one fields were sampled in 1937, and 5 of these showed no 
infestation. The number of larvae per square yard in the infested fields 
ranged from 8 to 1,041, or from 38,720 to 5,038,440 per acre. The intercrops 
in cornfields were velvetbeans or peanuts. 
Forty-five fields were sampled in 1938, and 3 of these showed no 
infestation. The number of larvae per square yard in the infested fields 
ranged from 4 to 768, or from 19,360 to 3,717,120 per acre. The intercrops 
Number 
Crop 
of fields 
1937 
1938 
Cotton 
13 
12 
Corn 
5 
8 
Peanuts 
12 
7 
Cotton (intercropped) 
1 
Corn (intercropped) 
10 
18 
