32 BULLETIN 746, U. S. DEPARTMENT OP AGRICULTURE. 
age annual infestation has been determined to be 58.2 per cent, or 
over half the canes infested. In 1912 the general average was 50.1 
per cent, in 1913 it was 52.4 per cent, in 1911 it reached the high 
figure of 73.9 per cent, while in 1915 the average sank to 51.5 per 
cent. The average was again high in 1916, being 75.5 per cent, but 
in 1917 it was 18.8 per cent, the lowest during the six years. In 
some localities an infestation of 100 per cent is sometimes reached, 
or all canes infested, while in others the damage may be 30 per cent 
or lower. 
Continuous observations have not been made in Texas, but in the 
lower Eio Grande Valley, to which the borer is limited at present, 
casual inspections usually reveal an infestation of nearly 100 per 
cent. 
VAEIATIONS IX INFESTATION. 
The infestation of different fields of sugar cane in the sugar-pro- 
ducing region varies from a low percentage to 100 per cent, or every 
cane infested. Conflicting opinions are held by different planters 
as to the infestation of the different varieties of cane and the in- 
festation in different years of growth. It has not been found that 
one common variety is more resistant to the moth borer than an- 
other, or that plant cane is more infested or less infested than first 
or second year stubble. 1 Another popular belief is that cane grown 
on sandy land is likely to be more heavily infested than cane grown 
on heavy soil. Examinations do not show that this is true, but the 
belief may have some basis, because it has been found that moths can 
emerge more readily from canes planted in sandy soil than from 
those planted in clay soil. The idea is also held that land treated 
with stable manure or cottonseed meal will be more heavily infested, 
but the data on the subject are insufficient to warrant any conclusion. 
MANY LAKYJE CRUSHED IX THE MILL. 
The greater number of moth borers in the larva stage in the late 
fall and early winter which would otherwise hibernate remain in the 
stalks of cane after they are cut. An examination of bored stalks 
at Audubon Park just before grinding yielded the information that 
38 per cent of the stalks contained borers. When the stalks are 
ground in the mill these larvae are crushed with the cane, leaving 
only such borers as may be in the stubble, seed cane, scraps of cane 
left about the plantations, cane tops, and Johnson grass and other 
grasses to start the infestation the following year. 
1 In 1918, however, 10.000 stalks of cane were examined on a group of sis plantations, 
the examinations being well distributed and evenly divided between plant and stubble cane. 
It was found that the general average for plant cane on each plantation was invariably 
higher than for stubble, though there were wide variations among certain fields and parts 
of fields, both of plant and stubble cane. Examinations on a much smaller scale, made 
in previous years, did not indicate any difference in favor of either plant or stubble. 
