4:2 BULLETIN 918, U. S. DEPARTMENT OE AGRICTTLTTIBE. 
Table XXI shows that no live larva? were found during May and 
June among those removed from seed and lint or in double seed 
buried in the irrigated plots (Experiments Nos. 557 and 558 A to D). 
and that 12.S per cent were alive or had emerged as moths under the 
same conditions in the nonirrigated plot (Experiments Nos. 560 and 
561 A to C). No live larva? were found in bolls buried in irrigated 
plots from March 10 (the first examination) until June 6 in Experi- 
ment Xo. 559 A, and none in bolls buried in nonirrigated plot (Experi- 
ment No. 562 A) after April 24. The surrounding soil had been irri- 
gated and when the last examination was made on June 7 the soil in 
the nonirrigated plot was found moist about 3 inches below the surface 
from water that had seeped in from below. From this experiment 
6.2 per cent survived till April 24. There was less mortality in the 
bolls when left on the surface of the ground than when buried. In 
the irrigated plot (Experiment No. 559 B) live larva? were found in 
bolls left on the surface of the ground at the last examination on 
June 4, 1919, and 9.7 per cent had survived or previously emerged 
as moths on this date. On the nonirrigated plot (Experiment No. 
562 B) 50 per cent of the larva? in bolls on the surface were alive on 
June 7, 1919. At the next examination, on July 25, all of the larva? 
were dead. 
In all of the experiments, especially the later examinations, many 
of the larva? were not recovered because the dead larva? were so decom- 
posed they were not recognizable. Very few if any escaped, for the 
buried bolls had close-mesh wire screen over the top and along the 
sides, extending below the level of the bolls. The earth surrounding 
the material was carefully sifted and larva? and pupal skins found 
here counted with the others. The percentages of mortality for the 
bolls are based on the number of larva? found in the samples at the 
beginning of the experiments. This is not absolutely accurate, 
because the number of larva? may vary considerably in individual 
bolls, but it is the most reliable figure to use inasmuch as the actual 
number of dead larva? could not be determined. 
It is seen that the mortality increases as the season advances, even 
where the conditions were most favorable, no live larva? being found 
as late as July 25, and that the mortality in all the experiments was 
greater when the larva? were buried than when they were left on the 
surf ace, and greater when the plots were irrigated than when left dry. 
These experiments also show that the greatest danger for starting 
a new infestation from material left in the fields is the old bolls 
left on the surface of the ground. Over 9 per cent of the larva? in 
these bolls on the irrigated plot survived till June 4 and 50 per cent 
survived in the nonirrigated plot. At this season the cotton will be 
large enough for oviposition to begin. Under the usual field condi- 
tions the irrigated lands will have been cultivated before this date 
