58 BULLETIN 746, U. S. DEPARTMENT OF AGRICULTURE. 
looked and the infestation is not known, but at two places in the 
vicinity, D and DD, both burned over, the infestation was 77 per cent 
and 75 per cent, respectively. The map will convey a more accurate 
idea of the situation than any further explanation, but the following 
points should be noted : At the two burned-over plantations, D and 
DD, farthest away from unburned fields, the infestation was high, 
about 75 per cent. At the two partly burned plantations, C and OC, 
it was medium, about 55 per cent. At the burned-over plantation B, 
bordered on each side by unburned or partly burned fields, it was 
also medium, 49.5 per cent. At plantation A, not burned and the 
center of a nonburning region, the infestation was the lowest of all, 
only 22.5 per cent. 
It is evident that a plantation must be considered as a unit in 
determining the infestation. The former custom was to consider a 
field as a unit, to which there is the objection that the moths of the 
borer can fly readily and doubtless reinfest areas in which the para- 
sites have gained the ascendency. Although a comparison of fields 
at Audubon Park is not unsatisfactory, it is true that the fields there 
are small, and they are not surrounded by vast stretches of cane and 
cornfields which are typical of the sugar parishes. 
The results in 1917 indicate that nonburning will be effective, on 
isolated areas of any size and on nonisolated areas so large that the 
bordering burned-over fields will have little effect on the general 
infestation. An illustration of nonburning on a single narrow 
plantation surrounded by burned-over areas was obtained in 1917. 
In this case nonburning was apparently of no benefit, the infestation 
being slightly, if any, lower than at a neighboring place. Yet the 
benefit to the land of plowing under the trash is considerable, and 
as it is only by degrees that the new practice will become established 
no planter should hesitate to practice nonburning because his neigh- 
bor refuses to do so. 
A planter who has plowed under his trash tells us that it maintains 
the tilth of the soil from year to year, and the difference between the 
condition of the soil where trash has been plowed under and where 
it has been burned is immediately perceptible. Where the trash is 
plowed under the soil is left open and porous and is enriched by the 
nitrogen and other fertilizing elements of the decaying vegetation. 
(See PL IX, fig. 1.) 
The work of plowing out the trash in the spring is regarded by 
some planters as so great that they refuse to leave it on the fields 
unburned. At the Sugar Experiment Station the process of caring 
for the trash, quoting Mr. W. T. Taggart, assistant director, is as 
follows : 
In plowing under cane tops, especially on land where stubble is to be held 
for the following year, the work must be done in such a manner as not to 
