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to pupate in the summer of 1938 were from eggs that hatched in November 
1937. 
These full-grown larvae which fail to pupate during the summer 
have been termed "carry-over" larvae. No reason is known for this carry- 
over of apparently mature larvae, nor is it known whether they develop to 
adults the following year or die as larvae. The number of carry-over larvae 
in the rearing cylinders was very small. Under field conditions in cropped 
areas the carry-over in 1938 was found to be 0.8 larva per square yard, and 
the emergence in the same fields was 23.5 beetles per square yard. The 
carry-over is apparently greater in noncultivated land than in cultivated 
fields. 
The newly emerged larvae are capable of living for a long period 
without food. On August 13, 1937, newly emerged larvae were confined in 
salve boxes without food, soil, or moisture. The average length of life 
for these larvae was 24.2 days. On September 1, or 19 days after hatching, 
49.7 percent were alive. One month after hatching 29.4 percent were alive. 
The last larvae lived through October 24, or 73 days. 
Thus far it has not been definitely determined how important fresh 
plant roots are to the development of the larvae. Large well-developed 
larvae deprived of plant roots but kept in moistened soil after February 
16, 1938, completed development to adults as well as those given fresh plant 
roots. A few medium-sized but no small larvae receiving similar treatment 
matured to adults without feeding on plant roots. In a limited number of 
rearing tests newly hatched larvae were placed in sifted soil devoid of 
plant roots, but all died before reaching maturity. 
Vertical distribution of larvae in the soil . — In order to determine 
the distribution of the larvae in the soil, diggings are being made in 
infested fields at intervals. The larvae are removed from the soil by a 
combination process involving washing through a series of screens and flo- 
tation in a heavy solution. It is realized that soil type, soil moisture, 
available food material, and possibly soil temperature affect the vertical 
distribution of the larvae. Usually the distribution is the result of a 
combination of these factors. Because it is impossible, in the preliminary 
work, to separate the results of the diggings and to group them satisfac- 
torily according to the factors involved, the vertical distribution of the 
larvae for all diggings made on or near a definite date are grouped together 
in table 8. 
