BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 71 
first two applications in an effort to control an infestation of leaf- 
hoppers on the young cabbage. The cost of this program amounted 
to $19.50 per acre. 
Harvest records from this planting showed an actual yield of 11.2 
tons per acre of U. S. No. 1 grade cabbage, which represented the 
yield of only 87.5 percent of the plants. The loss of 12.5 percent 
of the plants, or the equivalent of approximately 3,200 pounds of 
cabbage, was divided as follows: 3.5 percent, or 896 pounds, from 
damage by the imported cabbageworm, the cabbage looper, and larvae 
of the diamondback moth ; 2 percent, or 512 pounds, from damage by 
the corn earworm and cutworms; and 7 percent, or 1,792 pounds, from 
other kinds of damage, principally from abnormally cold weather. 
On the basis of a market value of 1 cent per pound for U. S. No. 1 
grade cabbage, this planting suffered an actual loss from insect dam- 
age of only 5^2 percent, or $14.08 per acre. Careful studies con- 
ducted during several years, however, show that growers suffer a loss 
of 20 percent of their cabbage crops annually from insect damage, 
despite control measures. An equivalent loss in this experimental 
commercial planting would have amounted to $51.20 per acre. 
The success of this program cannot be ascribed to greater effective- 
ness of the insecticides used, because studies have shown that those 
used by the growers are as effective as the ones substituted. Instead, 
evidence indicates that the superior effectiveness of the control pro- 
gram followed was due, primarily, to thorough application of the 
insecticides at regular intervals throughout the period when the cab- 
bage was subject to insect attacks. It may be considered, therefore, 
that an insecticidal program has been developed which, when sys- 
tematically and thoroughly applied, will give good control of cabbage 
caterpillars. Moreover, the proper use of this program successfully 
avoids the presence of poisonous insecticidal deposits on the marketed 
cabbage. 
TOBACCO INSECTS 
OUTBREAK OF THE TOBACCO MOTH IN GKOWKRS' PACK HOUSES 
Until the fall of 1938 depredations of the tobacco moth have been 
confined principally to flue-cured or imported tobacco packed in hogs- 
heads or other containers and stored in warehouses. Discovery of the 
moth in growers' pack houses in the fall of 1938 and in subsequent 
surveys, however, shows this pest to be a menace to the producer of 
flue-cured tobacco in North Carolina and Virginia. 
A single infestation of the tobacco moth in a growers pack house 
was recorded in 1937. By late summer and the early fall of 1938 it 
became evident that this insect was to be found in many widely sep- 
arated areas and was damaging tobacco in many pack houses, par- 
ticularly those near the storage centers of Durham, Reidsville, and 
Winston-Salem, N. C, and Danville, Va. While in general the dam- 
age observed in the fall of 1938 was fairly light, in the most severely 
damaged pack houses there was practically a complete loss of the 
newly harvested and cured crop. 
A more intensive survey for moth-infested pack houses was made 
during the period August 1 to December 15, 1939, and in this survey 
one or more inspections were made in 371 widely separated pack 
